Mark the true statements.

{1,2} is a subset of the power set of {1,2,3}. ( )

{{1,2}} is a subset of the power set of {1,2,3}. ()

The power set of the power set of the empty set is left curly bracket space space left curly bracket empty set comma space left curly bracket empty set right curly bracket right curly bracket space space right curly bracket . ( )

{1,2} is an element of the power set of {1,2,3}. ( )

The power set of the power set of the empty set is left curly bracket space empty set comma space left curly bracket empty set right curly bracket space right curly bracket .()

{{1,2}} is an element of the power set of {1,2,3}. ()

The set left curly bracket space left curly bracket right curly bracket space right curly bracket is not empty. ()

The power set of the empty set is the empty set. ()

The power set of the empty set is left curly bracket space empty set space right curly bracket . ()

The power set of the power set of the empty set is left curly bracket space empty set comma space empty set space right curly bracket .()