The elongation of the bar due to self weight is:

Question

A solid uniform metal bar of diameter D and length L is hanging vertically from its upper end. The elongation of the bar due to self weight is:                     

(a)  Proportional to L and inversely proportional to D²

(b)  Proportional to L² and inversely proportional to D²

(c) Proportional of L but independent of D

(d) Proportional of L² but independent of D