If circles x and y have the same area and circle x has a circumference of 10π, half of the radius of circle y is:  Choose the most appropriate option
A) 16
B) 8
C) 4
D) 2.5
E) 1

Rationale: "x be radius of circle x y be radius of circle y given : pi * x ^ 2 = pi * y ^ 2 also , 2 * pi * x = 10 * pi x = 5 thus y = 5 y / 2 = 2.5 ans : d"
Answer: D