Which term refers to the action of placing or retaining data in a memory unit?

The term that accurately describes the action of placing or retaining data in a memory unit is "store." In computing, storing data involves saving it into a memory space for later retrieval and use. This can refer to various types of memory, including RAM (Random Access Memory), hard drives, and cloud storage, where data needs to be retained for future access.

"Save" is often associated with the process of writing data to persistent storage, but it is not specifically about the action of retaining data in memory. "Keep" is a more general term that lacks the technical specificity required in this context and is not commonly used in the field of computer science to refer to data handling. "Cache," while related to data storage, specifically refers to a type of fast, temporary storage designed to speed up retrieval processes and does not encompass the broader concept of storing data in memory. Thus, "store" is the most precise and relevant choice in this scenario.