Answer:
Angle BFC
Explanation:
When an angle is complementary to another angle, that means they sum to 90 degrees.
Angle EFD is vertical to Angle AFC, so they are congruent. Because angle EFD is 90 degrees, and angle AFC is congruent, it is also 90 degrees.
So, we see, angle AFB + angle BFC = 90 degrees.
Angle BFC is complementary to AFB
It may seem confusing that it says 'select all that apply', and we only pick one answer, but trust the math. I have been on IXL myself, and have seen that even though it says 'select all that apply', there may only be one answer.
Hope this helps you! :)