I really need help ASAP

I wanna say it’s C because -4+4 does equal zero. But the directions aren’t to clear. But that would be my answer.

“exterior angles of triangles. an exterior (or external) angle is the angle between one side of a triangle and the extension of an adjacent side. try this drag the orange dots on any vertex to reshape the triangle.” look to get to the answer i explained what it means and other things i hope it you .