q: What do mollusks have?
Options:
- (A) aerobic capacity
- (B) Energy
- (C) gastropod shells
- (D) Chemical energy
- (E) a cuticle
- (F) kinetic energy
- (G) soft bodies
- (H) alveoli
a: (G)... Explanation: Mollusks are invertebrates such as the common snail. Mollusks are soft-bodied invertebrates. Mollusks, like the snail, are soft-bodied. That's why the answer is (G).

q: Sharks have as skeleton that contains
Options:
- (A) elastin
- (B) Epidermis
- (C) calcium
- (D) fur and fat
- (E) marrow
- (F) strength
- (G) all matter
- (H) collagen
a: (H)... Explanation: Cartilage is a tough tissue that contains a protein called collagen. Sharks have a cartilage skeleton. Sharks have as skeleton that contains a protein called collagen. That's why the answer is (H).

q: What happens to brain cells when the air supply is cut off?
Options:
- (A) strangulation
- (B) breathe
- (C) lead poisoning
- (D) death
- (E) hippocampus
- (F) painful
- (G) loss
- (H) die
a: (D)... Explanation: Brain cells die quickly if their oxygen supply is cut off. Air contains oxygen. Brain cells die quickly if their air supply is cut off. That's why the answer is (D).

q: What are molecules that are recognized by the body as alien?
Options:
- (A) parasites
- (B) Acids
- (C) heat or cold
- (D) negative
- (E) antigone
- (F) antibodies
- (G) antigens
- (H) blood cells
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
(G)... Explanation: Antigens are molecules that the immune system recognizes as foreign to the body. Yes, foreigners are called Aliens. Antigens are molecules that the immune system recognizes as alien to the body. That's why the answer is (G).