In relation to contractual performance, which of the following is incorrect?

A person who has substantially performed the contract is entitled to the contract price less so much as is necessary to repair the defects.

If one party is prevented from performing the contract by the other party, he or she may claim compensation on a "quantum meruit" basis.

A person who has carried out part of the contract is always entitled to a part of the contract price.

A person who has carried out all of his contractual obligations is entitled to all of the contract price.