Final answer:
Activity heads typically use red ink for editing documents because it clearly distinguishes their corrections from the original black text.
Step-by-step explanation:
When an activity head is editing documents or providing feedback, they often use red ink. This is because red stands out against black text, making it easier to see the corrections. Inkjet printers and xerography employ different methods and colors for producing images and texts on paper. The red ink corresponds to edits made directly to a document, where added text shows up in red, and deleted text is indicated with red text having a strikethrough. This convention helps in distinguishing the original text from the edits.
However, not all editing processes use actual ink, as with digital documents and modern printing technologies. Inkjet printers, for example, can create color images on paper using black, cyan, magenta, and yellow jets, while xerography is more complex and requires multiple drums and toners.