Water is being filled at the rate of $1 \mathrm{~cm}^3 \mathrm{sec}^{-1}$ in a right circular conical vessel (vertex downwards) of height 35 cm and diameter 14 cm. When the height of the water level is 10 cm, the rate (in $\mathrm{cm}^2 \mathrm{sec}^{-1}$) at which the wet conical surface area of the vessel increases is\\
(1) 5\\
(2) $\frac{\sqrt{21}}{5}$\\
(3) $\frac{\sqrt{26}}{5}$\\
(4) $\frac{\sqrt{26}}{10}$