The mechanical advantage of a lever is 4 What does it mean?​

1. efficient use of space

2. elimination of groundwater contamination

3. energy generation

4. lower carbon footprint

bacterium is not correct

not always but somethings can be reproduced in a laboratory.

well, since there is no answer choices, i will give an answer on how it works : )

the two objects are placed together. energy will always be transferred from the hotter object to the cooler object until they are equal. hope this is close to one of the answer choices : )