Answer
$\{\emptyset\} \in \{\emptyset, \{\emptyset\}\}$ is true
Work Step by Step
$\{\emptyset\} \in \{\emptyset, \{\emptyset\}\}$
This is correct.
Let's say $A=\{\emptyset\}$ and then substitute:
$A \in \{\emptyset, A\}$
This makes it clear, as $A$ is an element of a set that contains $A$.
