correct answer is : a) Tell him that you like him.
Explanation: there're some signs to identify imperative sentence .
- the sentence can be started by the verb
- Imperative sentence means command, prohibition, request etc. Whenever you'll see a sentence that indicates command, prohibition or request , you've to understand that's imperative sentence
- Also imperative sentence startswith let/ let's/ let him/let her/let (anyone's name)/let them