Which of the following is a common sign of pain in animals?

Increased vocalizations is indeed a common sign of pain in animals. When animals are in distress or discomfort, they may vocalize more than usual as a way to express their pain or communicate their needs. This vocalization could manifest as whimpering, growling, yowling, or excessive barking, depending on the species.

The other options do not reflect typical behavioral changes associated with pain. Improved appetite or increased energy levels are generally signs of good health rather than indicators of pain. Similarly, calm behavior is often associated with comfort or relaxation; thus, it is less likely to be found in animals experiencing pain. Recognizing these signs is crucial for veterinary technicians in assessing an animal's welfare and determining the need for further evaluation or treatment.