Which of the following is NOT a subset of $2$ to the power of left curly bracket a comma b right curly bracket end exponent cross times left curly bracket a comma b right curly bracket

Group of answer choices

$(\{$a$\},$ a$)$

$($a $,\{$a$\})$

$(\{$a$,$b$\},\{$a$,$b$\})$

$(\{$a$\},\{$a$,$b$\})$

$(\{$b$\},$ a $)$

$(\{$a$,$b$\},$ a $)$

$(,$ b$)$

$(\{$b$\},)$

$(\{$a$,$b$\},$ b$)$

$($ b $,\{$a$\})$