sinc function

Ask

The $sinc (\lambda)$ function which is used widely in communication, becomes zero when
(a)$π\lambda = \infty$
(b)$sin(π\lambda)=0$
(c))both (a) & (b)
(d)cannot determine

Answer is (c)

Concept

$sinc(\lambda) = \frac{sin(\lambda)}{\pi\lambda}$

For the sinc function to become zero