The ratio of the radius of two circles is 2: 7, and then the ratio of their areas is? Choose the correct choice from the following options:
A) 1:7 B) 2:9 C) 1:9 D) 4:49 E) 3:4
r1: r2 = 2: 7   Î r1^2: Î r2^2   r1^2: r2^2 = 4:49   Answer: 4:49
<result>D</result>
The ratio of the radius of two circles is 2: 7, and then the ratio of their areas is?