Give DFA's accepting the following languages over the alphabet $\{0,1\}$ :

$($a$)$ The set of all strings with $101$ as a substring. Prove the correctness of your DFA using state invariants.

$($b$)$ The set of all strings with the $11$ as a substring. Prove that your DFA has a minimal number of states.

$($c$)$ The set of strings ending in $110.($no proofs required here$)$