Final answer:
The term not used as a guide word in e-mails or memos is 'RESPONSE'. Guide words like TO, FROM, and DATE are typically used to indicate the recipient, sender, and date of the communication. The correct option is (c).
Step-by-step explanation:
The answer to which of the following is NOT a guide word used in e-mail messages and memos is c.RESPONSE.
Typical guide words in email messages and memos include TO, which indicates the recipient of the message; FROM, indicating the sender; and DATE, which provides the date the message was sent.
The term 'RESPONSE' is not typically used as a guide word at the top of e-mails and memos. Instead, it might be used within the text to refer to a reply or an answer to a previous message.