Answer:
The answer is A. Mutual mistake
Step-by-step explanation:
A contract is an agreement ( whether written or verbal ) between two parties that is legally binding.
A mutual mistake occur in a contract when both parties to a contract are mistaken about a material fact. It is a situation where the parties to a contract have identical misconception about a material fact in the contract.
In the explanation given in the contract between Randolf and the Art gallery manager, it is obvious that the art painting that is to be bought and sold was not well clarified by both parties, and the art manager acted based on an invalid assumption.
Hence the correct answer to this question is A. Mutual mistake