If $V_{peak} $ is the peak value of the input sinusoidal wave for half wave rectifier the average value of output or DC value =$ \large\frac{V_{Peak}}{\pi}$
$\therefore V_{DC}=\large\frac{V_{peak}}{\pi}$
$V_{DC}=\large\frac{10}{\pi}\;$$volts$
$\therefore V_{peak}=\large\frac{10}{\pi} \times \pi $
$\qquad= 10\;volts$
Hence b is the correct answer.