Which statement best describes why a machine is useful?
A machine does a greater amount of work than the amount of work that is done on it.
Amachine does a smaller amount of work than the amount of work that is done on it.
Amachine can decrease both the input force and the input distance needed to do a given amount of work.
A machine can decrease either the input force or the input distance needed to do a given amount of work.

A machine can decrease either the input force or the input distance needed to do a given amount of work.

Answer

A machine can decrease both the input force and the input distance needed to do a given amount of work.

Explanation:

It's a matter of elimination. The first one is not a bad choice, let's keep looking thoug. The second choice, if it does a little amount of work, than how is it being called useful? Eliminate. Third choice this is the correct answer becasue if you compare it with last and first choice it is the better out of the  two.

hammurabi rulers

good lesson

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.