Which of the Following Is Not an Ultimate Explanation for Behavior

Which of the following is not an ultimate explanation for behavior?

A) Birds migrate south because resources are more plentiful there during the winter months.
B) A fruit fly orients toward a patch of rotting fruit when odor molecules bind to receptors on its antennae.
C) A gazelle jumps in the air when a predator approaches to signal that it is healthy and not worth approaching.
D) A jellyfish migrates up toward light during the day because food resources are plentiful there.