A "kilogram" is a unit of measurement used to measure "weight." So, to solve this analogy you need to determine what it is that a "megabyte" is used to measure. The correct answer is "information." A "byte" is a unit of measurement used to measure "information" or computer memory. 

"Hertz" is a unit of measurement, used to measure the "frequency" of waves. So, to solve this analogy you need to determine what a "watt" is used to measure. The correct answer is that a "watt" is a unit of measurement, used to measure "power," particularly the "power" in an electrical circuit.

"Salinity" is a measure of how much "salt" there is in something, how salty something is. So, to solve this analogy you need to determine what "validity" measures. Well, "validity" means how valid something is, how much "truth" there is in a statement.

"Pounds" are a unit of measurement for "weight." So, we're looking for the word that describes the thing of which "degrees Celsius" is a unit of measurement, which is temperature.

"Quantum" is a unit of measuring "energy." So, to solve this analogy you need to determine what is measured in "leagues." Well, a "league" is a measure of "distance," not commonly used, equivalent to roughly three miles.

Since pins are stored in pincushions, we need to pick out an answer choice in which the first word describes a container for the second word. Since "scabbard" is defined as a sheath for a blade, a scabbard is a kind of case for a sword, so "sword is to scabbard" is the correct answer.

Ink is a part of a pen, specifically the liquid a pen is filled with. In trying to replicate this relationship, we must ask of the answer choices, "Which one of these is filled with water?" While "rain" may initially seem like a good answer, water constitutes rain—it doesn't fill it. Because water fills a fish tank, "fish tank" is the correct answer.

A "trinket" is a small item of little value. The word can describe either jewelry of this type or small items that might be set out as a humble ornament (like a small porcelain statue or something of that sort). Such trinkets can be placed on a shelf, and this makes the most sense among the possible sense of this analogy, given the potential answers. We can say that just as a trinket is placed on a shelf, so too can a tool be placed in a belt. (There are tool belts used by people working with tools.)

An “archive” is “a collection of historical documents or records.” So, because an archive is a collection of records, we need to pick out a noun that describes what constitutes a cookbook, or in other words, of what a cookbook is a collection. While “recipes,” “food,” and “ingredients” might each look like a potentially correct answer, “cookbook” is defined as “a book containing recipes,” so “recipes” is the correct answer.

A pallet is a thin, flat bed, usually filled with straw. A featherbed is filled with feathers, of which eiderdown is considered the best type for filling bedding.