Final answer:
Brenda pressed a function key, specifically the F7 key, which is usually used to initiate the spell check or proofreading feature in word processing software.
Step-by-step explanation:
Brenda pressed the F7 key on her keyboard while using a word processor. In most programs, including Microsoft Word, pressing F7 initiates the spell check or proofreading feature. The F7 key is considered a function key. Function keys are a set of keys at the top of most keyboards, which are labeled F1 through F12. Each function key, when pressed, can perform a specific task programmed by the software being used or by the operating system. They help to perform operations more quickly than using a mouse or navigating through menu options.
In the context of computer keyboards, we have keys that fall into different categories such as alphabetic, numeric, punctuation, and control keys. Since the F7 key is neither alphabetic (like A-Z keys), numeric (like the number pad keys), punctuation (like comma, period, etc.), nor a control key (like Ctrl or Alt), it fits best in the function key category which is designated for performing special operations in software applications.