[Q] Ethologists study how animals behave in animals'
Options:
- (A) Summer
- (B) state
- (C) Birds
- (D) life
- (E) seasons
- (F) health
- (G) homes
- (H) fields
[A] Here's my solution: Ethologists usually study how animals behave in their natural environment. Environments are animals homes. Ethologists usually study how animals behave in the animals' homes. The answer is (G).

[Q] All chemical reactions require a form of what to get started?
Options:
- (A) oxygen
- (B) celestial measurement
- (C) gas
- (D) heat
- (E) UV
- (F) charge
- (G) Light
- (H) scientific expression
[A] Here's my solution: All chemical reactions require activation energy to get started. Basically, heat is energy. All chemical reactions require heat to get started. The answer is (D).

[Q] What kind of animal is classified as having a vertebrae?
Options:
- (A) it keeps an organism warm
- (B) invertebrate
- (C) vertebrate chordate
- (D) gastropod shells
- (E) the body's largest organ
- (F) remains of prehistoric life
- (G) hard boned animals
- (H) roundworm
[A] Here's my solution: Vertebrate chordates have a backbone. Invertebrates have no vertebrae or backbone. Vertebrate chordates have a vertebrae. The answer is (C).

[Q] Evolution occurs in response to what in life?
Options:
- (A) static events
- (B) global warming
- (C) that material's properties
- (D) changing phenomenon
- (E) major threat to health
- (F) changing tides
- (G) Animal survival
- (H) isolated events
[A]

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Here's my solution: Evolution occurs in response to a change in the environment. Different environments Life is a changing phenomenon. Evolution occurs in response to changing phenomenon in life. The answer is (D).