Are these languages regular or not? Yes$/$no plus the extra last two questions. Alphabet $\{$a$,$b$\}$ or

$\{0,1\}$

a$.$ strings with more a$\text{'}$s than b$\text{'}$s

b$.$ strings with a in the center

c$.$ a$^$n b$^(2$m$)$ n$,$ m$>=0$

d$.$ palindromes

e$.$ a$^$n b$^$m a$^$k$.$ n