Answer:
A
Step-by-step explanation:
Well B is strange. You might get them to make one complementary angle, but that has nothing to do with the Triangle sum theorem.
C is true. He is getting similar triangles, but that does not prove the Triangle sum theorem. So -- don't choose C
D is just taking up space so you get 4 choices.
The answer should be A but the problem is the tips of the angles should all come to the same place. I think it does mean A, but it is a bit awkwardly worded.