Question

Two adjacent angles whose exterior sides are opposite rays are complementary.

Answer 1

we know that

Two angles are Complementary when they add up to $90$ degrees and two angles are Supplementary when they add up to $180$ degrees

f the exterior sides are opposite rays, then a straight line forms and you have the two angles add to $180$ degrees

So

the angles are supplementary and not complementary

therefore

the answer is the option

Never

Answer 2

 opposite ray means a total of 180 degrees between the two angles, amd complementary angles equal 90.
so option C is correct 
hope this helps