Topsoil erosion is such a large problem because __________.
the developing world depends on crops grown in topsoil
the developed world depends on crops grown in topsoil
topsoil takes a long time to replenish
topsoil is found in such small quantities on the Earth’s surface
it exacerbates climate change and global warming
The practice of "slash and burn" is widely considered to be __________.
typical for tropical forests
not sustainable
a relatively new invention
found in high mountainous regions