The ratio of the radius of two circles is 1: 5, and then the ratio of their areas is?  Select the correct option:  A) 1 : 7  B) 2 : 9  C) 1 : 25  D) 3 : 7  E) 3 : 4

Rationale: "r 1 : r 2 = 1 : 5 î r 1 ^ 2 : î r 2 ^ 2 r 1 ^ 2 : r 2 ^ 2 = 1 : 25 answer : c"
Answer: C