Prove that the following languages over binary alphabet are context

free:

$($a$)$ All nonempty binary strings that start and end with the same

symbol.

$($b$)$ All strings of the form anbncm where n$,$ m are nonnegative integers.

$($c$)$ All binary strings that are of the from wwR for a binary string

w$.$ Here wR is simply the string w written in reverse order. For

example, for w $=1000,$ wR is $0001.$