Final answer:
The parts of a memo are subject, body, and date. Unlike a cover letter, a memo does not typically include a signature as it is an informal business document meant for internal communication, with the subject line acting as a concise summary of the content.
Step-by-step explanation:
When selecting the parts of a memo, the correct components would be the subject, the body, and the date. The signature is typically not included in a memo as it is a more informal business document compared to a cover letter. For instance, a cover letter includes components like the return address, inside address, greeting, body, closing, and your typed name with a signature. However, a memo, which is more succinct and meant for internal communication, would focus on the subject line, which reflects the main point, much like an essay title, and the body where the message is provided in detail. The date is also crucial in a memo for reference purposes. A cover letter, on the other hand, is a formal document that might accompany a resume and therefore requires a signature to personalize the document.