The answer is 2 because a and b are slowing it down by condensing it and then freezing it so its not one, b and c are opposites because b slows it down whereas c speeds it up so its not 3, and number 4 is the same explanation for number 3
hope you pass :)
<span>a change in allele frequencies in a population over time also known as evolution</span>
The two letters are B and A, in that order.
