What are,if any,the possible defenses against a valid contract which may cause it to be unenforceable?

Question

Quizplus · Accepted Answer

The validity of a contract can be challenged on the grounds of genuineness of assent (such as fraud, duress, undue influence, or mistake) or form (such as lack of capacity, illegal subject matter, or violation of public policy). If any of these factors are present, the contract may be considered unenforceable. The other options are not complete or accurate in their descriptions of possible defenses against a valid contract.

What Are,if Any,the Possible Defenses Against a Valid Contract Which