A boat having a length 4 m and breadth 2 m is floating on a lake. The boat sinks by 1cm when a man gets on it. The mass of the man is:  Select the correct option
A) 12 kg
B) 60 kg
C) 72 kg
D) 80 kg
E) none of these

Rationale: "explanation : volume of water displaced = ( 4 x 2 x 0.01 ) m 3 = 0.08 m 3 . ∴ mass of man = volume of water displaced x density of water = ( 0.08 x 1000 ) kg = 80 kg . answer : d"
Answer: D