Among the following , digit  has no reciprocal is       

Reciprocal : for any two rational numbers a,b if $a\times b=b\times a=1$, then a, b are said to be reciprocals to each other.

The reciprocal of $x$ is $\frac{1}{x}$

Option ( D ): reciprocal of  $0$ is $\frac{1}{0}$

If a rational number 0 divided by the number 1 is undefined.

$\therefore$ Every number has a reciprocal except 0