Answer:
A. m∠2 + m∠3
Explanation:
The exterior angle theorem states that the exterior angle formed when you extend the side of a triangle is equal to the sum of its non-adjacent angles.
So m∠4's non-adjacent angles are 2 and 3 NOT 1. Therefore, the measure of ∠4 = m∠2 + m∠3.
Hope this helps!