If Cheryl wishes for Paul to paint her shop instead, is this a valid contract type?

In this scenario, the situation likely describes a unilateral contract. A unilateral contract is formed when one party makes a promise in exchange for the performance of an act by another party. Here, if Cheryl wishes for Paul to paint her shop, she is expressing a desire for him to perform a specific action—in this case, painting. Paul is not required to accept the offer or complete the task, but if he does, that performance constitutes acceptance of Cheryl's offer, thereby creating a binding contract.

This type of contract is characterized by the fact that only one party makes a commitment upfront—Cheryl expresses a desire or an offer, and the contract comes into existence when Paul completes the painting. The important aspect here is that it is the act of painting that solidifies the agreement, differentiating it from a bilateral contract where both parties exchange mutual promises before any performance occurs.

In contrast, the other options are not the best fit for this context. A bilateral contract would require both parties to exchange promises, which is not described here. A written contract pertains to the formality of the agreement and is not inherently tied to the type of interaction. An express contract involves clear terms, which could potentially apply, but it doesn't capture the essence of the unilateral nature of