The coefficient of linear expansion of glass is $\alpha_{8}$ per ${ }^{\circ} \mathrm{C}$ and the cubical expansion of mercury is $\gamma_{m}$ per ${ }^{\circ} \mathrm{C}$. The volume of the bulb of a mercury thermometer at $0^{\circ} \mathrm{C}$ is $V_{0}$ and cross-section of the capillary is $A_{0}$. What is the. length of mercury column in capillary at $T^{\circ} \mathrm{C}$, if the mercury just fills the bulb at $0^{\circ} \mathrm{C}$ ?
(a) $\frac{V_{0} T\left(\gamma_{m}+3 \alpha_{p}\right)}{A_{0}\left(1+2 \alpha_{g} T\right)}$
(b) $\frac{V_{0} T\left(\gamma_{m}-3 \alpha_{Q}\right)}{A_{0}\left(1+2 \alpha_{g} T\right)}$
(c) $\frac{V_{0} T\left(\gamma_{m}+2 \alpha_{g}\right)}{A_{0}\left(1+3 \alpha_{g} T\right)}$
(d) $\frac{V_{0} T\left(\gamma_{m}-2 \alpha_{g}\right)}{A_{0}\left(1+3 \alpha_{\varphi} T\right)}$