What causes the sinking of water in the northern Atlantic Ocean, which helps to drive the Ocean Conveyor Belt? a.) The high salinity from the south warms and becomes less dense.
b.) The high salinity from the south cools and becomes denser.
c.) The low salinity from the south gains salt and becomes denser.
d.) The low salinity from the south loses salt and becomes less dense.

1. in the wild, male house finches (carpodus mexicanus) vary considerably in the amount of red pigmentation in their head and throat feathers, with colors ranging from pale yellow to bright red. these colors come from carotenoid pigments that are found in the birds' diets; no vertebrates are known to synthesize carotenoid pigments. thus, the brighter red the male's feathers are, the more successful he has been at acquiring the red carotenoid pigment by his food-gathering efforts (all other factors being equal). during breeding season, one should expect female house finches to prefer to mate with males with the brightest red feathers. which of the following is true of this situation? a. alleles that promote more efficient acquisition of carotenoid-containing foods by males should increase over the course of generations.b. alleles that promote more effective deposition of carotenoid pigments in the feathers of males should increase over the course of generations.c. there should be directional selection for bright red feathers in males.d. three of the statements are correct. e) two of the statements are correct.