Answer:
seller.
Step-by-step explanation:
A contingency is a term often used in real estate, to describes a form or set of conditions or clauses that must be fulfilled by either one or both of the parties, that is either buyer or seller or both of them, prior to the sales of estate properties.
While in most cases, contingency benefits the buyer, however, in a situation it benefits the seller, it is the seller's consent that is needed to remove the contingency.