Answer: The Answers are, A: happens all the time, D: can be caused by genetic drift, and E: can be caused by natural selection.
Addition, you added an extra T between the first A and C
<span>The formation of the fertilization envelope (slow-block to polyspermy) requires an increase in the availability of </span>calcium ions.
Slow-block to polyspermy is also called cortical reaction. In this reaction, the sperm will be permanently blocked by cortical granules. The release of calcium ion will trigger this reaction.
Coral snakes imitates king snake-mimicry
also body coverings such as fur on a bear