Answer:
a
Step-by-step explanation:
Another way to solve this is to use the Midpoint Formula. The midpoint of a segment joining points

and

is

So the midpoint of your segment is

Perhaps it helps to see that the x-coordinate of the midpoint is just the average of the x-coordinates of the points. Ditto for the y-coordinate of the midpoint; just average the y's.
(2-a)^2 + 3(2-a)
A^2 -2a + 4 + 6 -3a
A^2 -5a +10
The answer for this question is choice c. Memorization is not a good way to truly understand math. You want to understand the reasoning behind your answers always.
A math expert is what you should strive to be! The first two choices are great ways to become this.