Oscillations and Waves: JEE Main 2015 Physics question

A pendulum made of a uniform wire of cross sectional area $A$ has time period $T.$ When an additional mass $M$ is added to its bob, the time period changes to ${T_{M.}}$ If the Young's modulus of the material of the wire is $Y$ then ${1 \over Y}$ is equal to : ($g=$ $gravitational$ $acceleration$)