Fifty KJ of Heat Is Added to a 10-Kg Piece $\degree$

Fifty kJ of heat is added to a 10-kg piece of lead at its melting point of 330 $\degree$ C and 2 kg of lead melts. The heat of fusion of lead is

A) 2.5 kJ/kg.
B) 3.3 kJ/kg.
C) 5 kJ/kg.
D) 25 kJ/kg.