The answer would be A. Heritable variations for some traits
Variation in traits and characteristics is what drives natural selection. Organisms are naturally selected because of their phenotypes(physical characteristics) and some that have more suitable phenotypes are favored(they get to live longer and reproduce). If these variations didn’t exist no one would be favored and there’d be no natural selection or evolution basically:)
An example would be different fur colors for wolves that live in a mountain/polar ecosystem. One has white fur one has gray fur for example. The one with white fur would of course be naturally selected by the environment.
It takes time for a creature to adapt to its Environment. So that puts off 2.
Your guaranteed to get traits from your parents so that rules out #1
There isn't really an equal probability of survival for an offspring, ruling out #3.
So that leaves us with 4. I'm not biology expert, I'm just letting you know how I did this problem. Just in case i'm wrong, I would double check with other answers :)
