The raised cosine pulse $p(t)$ is used for zero ISI in digital communications. The expression for $p(t)$ with unity roll-off factor is given by $p(t)=\frac{\sin 4 \pi W t}{4 \pi W t\left(1-16 W^{2} t^{2}\right)}$. The value of $p(t)$ at $t=\frac{1}{4 W}$ is

- $-0.5$
- $0$
- $0.5$
- $\infty$