The ratio of the radius of two circles is 1: 3, and then the ratio of their areas is?	Select:  A) 1 : 5  B) 1 : 6  C) 1 : 9  D) 1 : 3  E) 1 : 2

Rationale: "r 1 : r 2 = 1 : 3 π r 12 : π r 22 r 12 : r 22 = 1 : 9 answer : c"
Answer: C