If the function $f(x)=\left\{\begin{array}{1 1}(\cos x)^{1/x}&x\neq 0\\k&x=0\end{array}\right.$ is continuous at $x=0$ then value of $K$ is

Question

$(a)\;1\qquad(b)\;-1\qquad(c)\;0\qquad(d)\;e$