P(0,0) and R(2b, 2c)
Midpoint:
x = (x1+x2)/2 and y=(y1+y2)/2
Midpoint PR
x = (0 + 2b)/2
= 2b/2
=b
y = (0 + 2c)/2
=2c/2
=c
Midpoint PR (b,c)
Answer is the last one
(b,c)