The Heating Coil of a Hot Water Heater Has a Resistance

Multiple Choice

The heating coil of a hot water heater has a resistance of 20 W and operates at 210 V.How long a time is required to raise the temperature of 200 kg of water from 15 $\degree$ C to 80 $\degree$ C? (The specific heat for water = 10³ cal/kg* $\degree$ C and 1.0 cal = 4.186 J) .

A) 1.7 h
B) 3.8 h
C) 5.1 h
D) 6.9 h