Given right triangle abc, which of the following statements must be true?

For this case we must take into account the following definition:
 Complementary angle: Angle that added to another form one of 90 degrees.
 Thus,
 Angle A and C are complementary.
 On the other hand, the following trigonometric relationship is fulfilled:
 sine (C) = cos (90-C)
 
 option A
 option D

Igot 108 hope that’s right !