Answer: the doctrine of merger is specified the way in which was enunciated in the question.
Explanation: there is no question here but the doctrine of merger is exactly enunciated in the question:
Under the doctrine of merger, the contract merges into the deed, and the terms of the contract are meaningless. Even though the contract specified a “good and marketable title,” it is the deed that controls, and the deed contained no covenants of title. A deed does not incorporate the title terms of a contract.