Answer
The answer is option (d) none of preceding
Work Step by Step
latent heat is the amount of heat released or absorbed by a substance during its phase change.
now let's check the options given to us:
(a), (b) is related to specific heat but we know that specific heat is the amount of heat required to increase the temperature of a mole of substance by 1 degree centigrade which is nowhere related to specific heat
(c) mechanical equivalent of heat means work, here work plays no role. so, option (d) none of the preceding is the correct option.
