Answer:
Answer is option c, i.e. unenforceable by any holder, including an HDC.
Explanation:
When any instrument is signed by a person, who has been declared mentally incompetent by a court, then such an instrument is considered void and it stands unenforceable by any holder including the holder in due course (an HDC). A mentally incompetent person does not have adequate knowledge of the activities carried by him/her and is not treated as a genuine.
