$1.$ For the following CFGs$,$ determine which of the strings, $\backslash$epsi $,$ abba, aaaaa, and b is generated.

a$.$ S $$ aS $|$ bS $|$ a $|$ b $|\backslash$epsi

b$.$ S $$ aaS $|$ aaaS $|$ a

c$.$ S $$ aX$|$ bS $|$ a $|$ b

X $$ aX $|$ a