What reminder did the clerk give me concerning the cheque?

The correct choice highlights the appropriate use of the verb "enclose" in this context. The phrase "to enclose a cheque" implies that the clerk is reminding you to place the cheque inside an envelope or a document, which is a common practice when sending payments or important documents. This wording suggests that the cheque should be physically included alongside other materials or paperwork being submitted.

The context calls for a specific action related to how the cheque should be handled or presented. In this case, "enclose" indicates a thoughtful preparation step often emphasized in formal or financial communications.

The other choices do not convey the same nuance: "attach" generally refers to digital communications or emails, while "include" is too vague and might not stress the physical aspect of how the cheque should be handled. "Send" focuses on the act of dispatching but lacks the specific instruction about the cheque's physical placement relative to other materials.