Ans: (E)
Question: Mammals generate heat mainly by what?
Options:
- (A) hugging mammals
- (B) calorie counting
- (C) with their fur
- (D) energy of moving objects
- (E) burning calories
- (F) sweating
- (G) selling fur coats
- (H) flow of electrons
CoT: Mammals generate heat mainly by keeping their metabolic rate high. And resting metabolic rate is a big contributor to calories burning. Mammals generate heat mainly by burning calories.

Ans: (D)
Question: What is an example of a tetrapod vertebrate?
Options:
- (A) genus
- (B) Leeuwenhoek
- (C) a fish
- (D) crocodile
- (E) animals
- (F) four limbs
- (G) warm-blooded
- (H) graptolites
CoT: Reptiles are a class of tetrapod vertebrates that produce amniotic eggs. Crocodiles, snakes, and lizards are all types of reptiles. Crocodiles are a type of tetrapod vertebrates that make amniotic eggs.

Ans: (C)
Question: What organ is harmed by air pollution?
Options:
- (A) piano
- (B) church organ
- (C) heart
- (D) harp
- (E) bushes
- (F) animals
- (G) eardrum
- (H) lungs
CoT: Air pollution harms the respiratory and circulatory systems. Sulfur dioxide can irritate the respiratory system and damage the heart and circulatory system. Air pollution damages the heart.