Answer:
q/b = r/c
Explanation:
We can determine which equation is correct by looking at the similar angles
A ~ P and B ~ Q so the side length that is between these angles would be proportional which are :
r/c
Next up
C ~ R and again B ~ Q and the side length that is between these angles:
q/b
so the answer is
q/b = r/c as given in last option