Answer & Explanation
A) 25 W
Resistances of both the bulbs are
R1=V^2/P1 = 220^2/25
R2 = V^2/P2 = 220^2/100
When connected in series, the voltages divide in them in the ratio of their resistances. The voltage of 440 V devides in such a way that voltage across 25 w bulb will be more than 220 V. Hence 25 w bulb will fuse.