Question

The number of subsets of the power set of a singleton set is

• A. $1$
• B. $2$
• C. $4$
• D. $16$

Answer 1

The correct option is C $4$

Let $X=\left\{p\right\}$
$P\left(X\right)=\{\varphi ,\{p\left\}\right\}$
$P\left(X\right)$ has $2$ elements.
$\Rightarrow$ Number of subsets of $P\left(X\right)$ is $2^2=4$