we know it can't be A. supplementary because that would be angle 2 and 4 or 1 and 3 (etc). It cant be B. verticle because that would be like 6 and 7 or 2 and 3 (etc). and it cant be D. Alternate interior angles because that would be 3 and 6 or 5 and 4 (etc). so the answer is C. alternate exterior.
