The ratio of the radius of two circles is 1: 3, and then the ratio of their areas is? Choose the correct choice from the following choices.
A) 1:7	B) 2:9	C) 1:9	D) 3:7	E) 3:4
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?