Part D
What is the measurement of angle C?

Step-by-step explanation:

I think we are missing some information (angle F or B or a side length would be great).

but just the right angles are not enough to calculate specific numbers. they would depend on the angle F or e.g. the side length of AB.

without any further information F and AB can be freely changed without changing the known facts, but it changes also C, B, G

so, all I can say is C = 180 - B.

and that G = B.