A bull's response to cow-to-cow mounting is described as an example of a visual cue.

This statement is **true**. The slides describe a bull being attracted to a particular cow in a herd by viewing cow-to-cow mounting. This is a **visual** communication cue, distinct from the olfactory cues also described in the same example.\n\n**Key takeaway:** A behavioral event can provide visual information that influences another animal.\n\n**Glossary:** **Visual cue**: Information received through sight; **behavioral cue**: An observable action that conveys information.