(b)
Let $I = \int_{0}^{\pi}{e^{\sin^{2}x}\cos^{3}{x\ dx}}$ …(i)
$\Rightarrow \ I = \int_{0}^{\pi}{e^{\sin^{2}{(\pi - x)}}{\cos^{3}(\pi -}{x)\ dx}}$
$\Rightarrow \ I = - \int_{0}^{\pi}{e^{\sin^{2}x}\cos^{3}{x\ dx}}$ …(ii)
On adding Eqs.(i) and (ii), we get
$2I = 0\ \Rightarrow \ I = 0$