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