Ans: B
Sol: Initially ice will absorb heat to raise it's temperature to 0oC then it's melting takes place
If m = Initial mass of ice, m' = Mass of ice that melts and mw = Initial mass of water
By Law of mixture Heat gain by ice = Heat loss by water

So final mass of water = Initial mass of water + Mass of ice that melts = 5 + 1= 6 kg.