$1\mathrm{.}41$ On a direct shear test, the normal and shear stress on failure plane at failure are $60\sqrt[\phantom{2}]{3}\frac{N}{m}{m}^2$ and $60\frac{N}{m}{m}^2$ respectively. The major stress at the time of failure is

$($a$)80\sqrt[\phantom{2}]{3}\frac{N}{m}{m}^2$

$($b$)120\frac{N}{m}{m}^2$

$($c$)80\frac{N}{m}{m}^2$

$($d$)120\sqrt[\phantom{2}]{3}\frac{N}{m}{m}^2$

$[$MSQ$]$