Explanation:

- Option 1: Inadequacy of consideration

- A contract usually requires valid consideration. However, the law does not generally concern itself with the adequacy of consideration as long as it's of value. Hence, inadequacy alone doesn’t void an agreement.

- Option 2: Agreement to agree in future

- An agreement to agree in the future is not a binding contract. It lacks certainty as the terms and commitments are not finalized.

- Option 3: Uncertainty

- If an agreement is too vague or lacks clear terms, it can be rendered void. "A agreed to pay when he wishes" is uncertain and lacks a definite obligation.

- Option 4: All of the above

- Since not all the provided options alone void the agreement, this option is incorrect.