For a contract to be valid it MUST

Notarization is not a requirement for all contracts to be valid. While certain types of contracts may need to be notarized for legal purposes (like real estate transactions), the essential element for any contract's validity is the presence of an offer and acceptance, not notarization.

While many contracts must be in writing to be enforceable, particularly those that fall under the Statute of Frauds, verbal agreements can still be valid in many situations. Therefore, the requirement of being in writing does not universally apply to all contracts, making it an insufficient criterion for validity.

Witness signatures may be required for specific types of contracts to enhance their validity or to meet jurisdictional requirements. However, the presence of a witness is not a universal necessity for a contract to be valid; the critical component is still the mutual agreement through offer and acceptance.