What is the ratio of the area of the inner square to the area of the outer square?
A: (a-b)2=b2/a2
B: a2-b2/a2
C: (a-b)2/(a+b)2
D: (ab)2/(a+b)2
A: (a-b)2=b2/a2
B: a2-b2/a2
C: (a-b)2/(a+b)2
D: (ab)2/(a+b)2