What concept determines the rights of parties once a valid land sale contract has been entered into?

The correct concept that determines the rights of parties once a valid land sale contract has been entered into is equitable conversion. Under the doctrine of equitable conversion, once a contract for the sale of land is executed, the purchaser acquires an equitable interest in the property, and the seller retains legal title until the transaction is completed. In essence, the buyer is considered the equitable owner of the property, and this status affects various rights and obligations of both parties.

Equitable conversion arises from the principle that the contract transforms the relationship between the buyer and seller; the buyer's equitable interest entitles them to enforce the terms of the contract and potentially seek specific performance if the seller refuses to convey legal title. This doctrine is especially important in the context of mortgage foreclosure, inheritance, and property claims, as it defines the rights of the parties involved.

Other concepts like equitable title and legal ownership are related but do not fully capture the implications of a valid land sale contract in the same way. Title insurance, while it provides protection against defects in the title, does not determine the rights of the parties post-contract execution. Therefore, equitable conversion aptly summarizes the legal and equitable ramifications of entering into a valid land sale contract.