Check again the amount by which current and power changed. They don't change by the same factor.
I royally screwed up .... I blame old age and senility
@imtiaz ... humble apologies answer b) current ..... should have been answer
10V x 1 A = 10 W
double the voltage, the current doubles as correctly stated but the power dissipated quadruples
20V x 2A = 40W
@gneill .... cheers