B.
Explanation:
to find the midpoint the formula is

so use the points provided and substitute them in to the formula!!
- (-4,-7) = (x1, y1)
- (5,6) = (x2, y2)
so now it would look like this inside the formula
and then you'll just solve that !!

so we know x = 0.5 now, solve for y

and we now know y = -0.5
point form (x,y) and you're all done !!
and this is why the answer is B. (0.5, -0.5)