首先比较的是复数的individuals，所以单数的A/E排除；B/C都是在比较one genetic composition, 排除，只剩D

"""the other"" is used when there are only two things.
i chose one of the two dinner options; my date chose the other.

""another"" is used for another of an indefinite number of things.
usually, i'll order one entree and my date will order another, so that we can each try some of both.

""each other"" refers to interaction between exactly two things or people.
my date and i usually sit next to each other, rather than across from each other.

""one another"" also refers to interaction, but there may be more than two things/people.
the holiday season offers many occasions for people who have not seen one another in many months to reunite."