What is a respiration challenge monkeys face in comparison to fish? A) Dry air makes it a challenge to keep respiratory structures moist. B) The surface area of respiratory structures is diminished in land animals. C) Air is denser than water and is harder to diffuse across respiratory surfaces. D) Air contains less oxygen than water and it is harder for respiratory structures to extract the viral oxygen.
Of the answers listed, the first one, letter (A) makes the most sense. "Dry air makes it a challenge to keep respiratory structures moist" would be a decided disadvantage against fish, who inhabit aquatic environments. Fish use gills to extract oxygen from water. The water is allowed to flow over the gills, so the gills have an unending moisture supply to keep them hydrated. Monkeys have to depend on the humidity factor of air to help keep the interior of their lungs moist.
It wouldn't be letter (B), as most lung structures in land animals are larger when compared to the fish's gills. Answer (C) is not a good choice either; air is certainly not denser than water, it is less dense and diffuses with relative ease across the alveoli structures within lungs. Answer selection (D) is off-base as well, air actually contains more oxygen than water and is easier to extract by breathing processes conducted by land-dwelling animals like monkeys.