What helps to insulate and protect the body?
Options:
- (A) tail fins
- (B) Animal fur
- (C) fur seals
- (D) keratin
- (E) nitrogen
- (F) snow
- (G) Epidermis
- (H) poultry
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Let's think first: Hair helps to insulate and protect the body. Hair is composed of the protein keratin. The protein keratin helps to insulate and protect the body.... So the answer is [(D)]


Flowing water from a mountain can dissolve carbon in what kind of rock?
Options:
- (A) magma
- (B) loose soil
- (C) loose dirt
- (D) precipitation
- (E) pumice
- (F) limestone
- (G) wind and rain
- (H) andesite
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Let's think first: Flowing water can slowly dissolve carbon in sedimentary rock. Limestone is a type of sedimentary rock. Flowing water can slowly dissolve carbon in limestone.... So the answer is [(F)]


What causes the penis to develop?
Options:
- (A) Creatine
- (B) Energy
- (C) Estrogen
- (D) Testicles
- (E) matter vibrating
- (F) Testosterone
- (G) movement
- (H) It expands
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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
Let's think first: Testosterone stimulates the reproductive organs to develop into male organs. Male mammals have a tube-like organ called the 'penis'. Testosterone causes the penis to develop.... So the answer is [(F)]