Question

Which of the following is the measure of ÐQRS?

Answer 1

That's a "right angle", measuring 90 degrees.

How we know this:
The only thing in the picture that tells us is the little square
drawn in the corner by ' R '.  That's the symbol that's used
on a drawing to show that an angle is 90 degrees. 

Without that little square, there's nothing else in the picture
to tell us the measurement of that angle.

Answer 2

It is C. 90 degrees because it is a right triangle