The ratio of the radius of two circles is 1: 5, and then the ratio of their areas is?	Choose the correct choice from the following answers:
A) 1:7  B) 2:9  C) 1:25  D) 3:7  E) 3:4
r1: r2 = 1: 5   Î r1^2: Î r2^2   r1^2: r2^2 = 1:25   Answer: 1:25
<result>C</result>
The ratio of the radius of two circles is 1: 5, and then the ratio of their areas is?