Under Section 10 of the Indian Contract Act, 1872, which of the following is NOT an essential element for a valid contract?

Section 10 states that all agreements are contracts if they are made by the free consent of parties competent to contract, for a lawful consideration and with a lawful object, and are not hereby expressly declared to be void. Registration is not a requirement under Section 10 for the validity of a contract under the Indian Contract Act. While certain specific statutes (such as the Registration Act, 1908 or the Transfer of Property Act, 1882) may require registration for particular types of transactions, the Contract Act itself does not impose any such general requirement. The elements of Section 10 are exhaustive for the purposes of this Act.