The ratio of the radius of two circles is 1: 3, and then the ratio of their areas is?
Select the correct option.
A) 1: 5
B) 1: 1
C) 1: 9
D) 1: 2
E) 1: 8
r1: r2 = 1: 3   Πr12: Πr22   r12: r22 = 1: 9.Answer: 1: 9
<result>C</result>
The ratio of the radius of two circles is 1: 3, and then the ratio of their areas is?