Two fuse wires A and B, each 5cm long and made of the same material, have cross-sectional areas 0.02mm2 and 0.05mm2 respectively. The same steady current of 3A passes through both wires for the same time. What is the ratio of heat produced in wire A to that in wire B?
a) 25:4
b) 2:5
c) 5:2
d) 1:1