Two rods (one semi-circular and other straight) of same material and of same cross-sectional area are joined as shown in the figure. The point A and B are material at different temperature. The ratio of heat transferred through a cross-section of a semi-circular rod to the heat transfer by straight rod in a given time is-
(A) 2:π
(B) 1:2
(C) π:2
(D) 3:2