Eliminate the answer choices which include the passive voice. This question also has to do with order of relevance. Consider that the initial prepositional phrase describes the guide's most relevant action. What is the most important thing the guide did? He cleared away the debris. That should be mentioned in the active voice before the fact that he allowed his group to follow his path. Choose the answer that most efficiently describes the primary action (in the active voice) and sets up the clauses about the consequences of his action.

"scheduled to take place at 2:00" is an appositive phrase, adding meaning to the subject "the seminal presentation. Appositive phrases such as these should be offset by commas at both beginning and end. Such phrases often rename the subject of a sentence.

"The music sharing service considered a threat to copyright protection" is a phrase modifying the subject noun "Napster." It is an appositive phrase and should, therefore, be offset by two commas. Appositives define or rename the subject of the sentence, in this case Napster (the subject) is being re-characterized as "the music sharing service considered a threat to copyright protection." The appositive must be offset with commas because it is outside of the fundamental grammatical structure of the sentence.

When a sentence begins with a dangling participle or descriptive phrase, the person or thing described in that phrase (in this case, "Neil") must immediately follow it. Only one answer choice does this correctly. The answer choice that begins "Neil's anxiety" may appear to do so, but it does not, because the possessive "Neil's" is no longer the subject, but is describing the anxiety.

After the comma we need the name of the person. In this sentence the dependent introductory clause (which is not underlined) is "her" which cannot describe a "toe." In order to fix this dangling modifier, the subject of the main clause needs to be changed to "the trapeze artist."

This sentence contains an error in parallelism. The verbs "travel" and "stay" must be in the same form. In the sentence as it is presented, "to travel" and "staying" do not match. The correct answer makes both of these terms infinitives: "to travel" and "to stay."

The answer choice "include family history, poor diet, and excessive stress" is correct because it contains appropriate parallelism—in this case, a list of three noun phrases.

The original text "include family history, poor diet, and having an excess of stress" and the answer choice "include family history, poor diet, and having an excessive amount of stress" contain faulty parallelism—the last item in the list includes the verb "having" whereas the first two items in the list do not employ verbs. These answers are therefore incorrect.

Answer choices "includes family history, poor diet, and excessive stress" and "tends to include family history, poor diet, and excessive stress" are incorrect because they both use singular predicates for the plural subject, "risk factors for cardiovascular disease."

Eliminate the answer choices which include the passive voice. This question also has to do with order of relevance. Consider that the initial prepositional phrase describes the guide's most relevant action. What is the most important thing the guide did? He cleared away the debris. That should be mentioned in the active voice before the fact that he allowed his group to follow his path. Choose the answer that most efficiently describes the primary action (in the active voice) and sets up the clauses about the consequences of his action.

Eliminate the answer choices that include the passive voice. This question also has to do with order of relevance. Consider that the initial prepositional phrase describes the forester's most relevant action. What is the most important thing the forester did? He cleared away the debris. That should be mentioned in the active voice before the fact that his action allowed his vehicle to pass. Choose the answer that most efficiently describes the primary action (in the active voice) and sets up the clauses about the consequence of his action. If the subject of the first clause is the forester "swinging" his axe, he must be the subject of the second clause to avoid a dangling modifier error.

In the sentence, "the thirteenth-century philosopher and theologian" is an appositive that renames "Thomas Aquinas"; appositives are set off by commas at both ends, as in the credited response. No comma is needed between "philosopher" and "theologian," however. Because "thirteenth-century" is being used as an adjective in this case a hyphen is needed.