Options:
$\left \{ \left ( b^{n}ab^{n}a\right )^{m} | n,m \geq 0 \right \}$
$\left \{ \left ( b^{n}ab^{n}a\right )^{m} | n,m \geq 0 \right \} \cup \left \{ b^{n} | n\geq 0 \right \}$
$\left \{ \left ( b^{n}ab^{n}\right )^{m}a | n,m \geq 0 \right \}$
$NONE$