Question

which statement describes natural selection?
it is the primary mechanism for evolution.
it must act on structural traits.
it acts to cause overpopulation.
it causes learned skills to become heritable traits.

Explanation:

• For the option "It is the primary mechanism for evolution": Natural selection is indeed the main process by which evolution occurs. Organisms with favorable traits survive and reproduce more, leading to changes in species over time.
• For "It must act on structural traits": Natural selection can act on various traits including behavioral, physiological, not just structural, so this is incorrect.
• For "It acts to cause overpopulation": Overpopulation is a result of high reproductive rates, and natural selection acts on the variation within populations (due to overpopulation - style competition), not to cause overpopulation.
• For "It causes learned skills to become heritable traits": Learned skills are not heritable as they don't change the genetic code, so natural selection can't make them heritable.

Answer:

A. It is the primary mechanism for evolution.