3. For what purpose are the points where Earth's axis of rotation intersects Earth's surface used?

The points at which Earth's axis of rotation intersects Earth's surface are used as reference points for defining direction. These points are the geographic North Pole and South Pole. Halfway between the poles, a circle called the equator divides Earth into the North and Southern Hemispheres.

Explanation:

b. the carbon cycle ensures living things have a source of hydrogen

the correct answer is option b

behavioral response need communication and thus co-ordination at several levels such as interaction among cells, organ system and the entire organism.

behavioral response produces both internal and environmental stimulus.