Power: the Voltage and Power Ratings of a Particular Light

Power: The voltage and power ratings of a particular light bulb, which are its normal operating values, are 110 V and 60 W. Assume the resistance of the filament of the bulb is constant and is independent of operating conditions. If the light bulb is operated with a current that is 50% of the current rating of the bulb, what is the actual power drawn by the bulb?

A) 10 W
B) 15 W
C) 20 W
D) 25 W
E) 30 W