A student obtains a blurred image of an object on a screen by using a concave mirror. In order to obtain a sharp image on the screen, he will have to shift the mirror

Question

$\begin{array}{1 1} (a)\; \text{towards the screen} \\ (b)\; \text{away from the screen} \\ (c)\; \text{either towards or away from the screen depending upon the position of the object} \\ (d)\; \text{to a position very far away from the screen} \end{array}$