Answer:
B. eliminate debts that they are unable to pay off
A) a barter system that does not rely on money or other currency.
Environmental uncertainty is affected by environmental complexity, change and resources. The correct option among all the options that are given in the question is the first option or option "a". Environment needs to be protected for the sake of survival of all living things. Any kind of uncertainty regarding environment can have a devastating effect.
Answer:
option d: can be accomplished by clicking one's tongue
Explanation:
Echolocation can be defined as a human unique capabilities or ability to notice (detection) objects in their environment through echoes sensing from those objects, by normally giving or creating sounds. Example is using your mouth to make clicking sound, tapping your foot.
