Which of the following can be a sign of pain in pets?

Restlessness or vocalization is a well-documented sign that pets may be experiencing pain. When in discomfort, many animals tend to exhibit increased agitation, pacing, or unusual vocalizations as a way to express their distress. It's important to recognize that pain can manifest in various behavioral changes.

Decreased appetite is another common indicator of pain in pets. Animals often reduce their food intake when they are unwell or in pain, as eating may exacerbate their discomfort or they may not feel up to eating at all.

Increased energy is generally not associated with pain. Typically, a higher level of energy and activity can indicate that a pet is comfortable and not experiencing any discomfort.

Therefore, considering restlessness and vocalization as well as decreased appetite, the most comprehensive answer that encompasses these signs is that all of the above can indicate different responses to pain. Hence, the answer includes A, B, and C.