Which of the following indicates a GCS of 13 or less?

A Glasgow Coma Scale (GCS) score of 13 or less indicates a moderate impairment in consciousness or responsiveness. The GCS assesses three aspects: eye opening, verbal response, and motor response. A score of 13 reflects situations where the patient's level of consciousness is altered, be it through confusion, disorientation, or other alterations in mental status.

An altered level of consciousness suggests that the individual may not be fully aware of their surroundings or may have reduced responsiveness, which aligns directly with a GCS of 13 or less. This metric is crucial in assessing neurological function and determining the need for further medical evaluation and intervention.

In contrast, while inability to speak could sometimes indicate a neurological issue, it doesn't specifically correlate with the GCS measurement as it does not provide a comprehensive view of the patient's responsiveness. High body temperature could point to infection or other medical issues but doesn't provide insights on consciousness. Bradycardia, or a slow heart rate, is a physiological observation that doesn't directly reflect the level of consciousness either. Thus, altered level of consciousness is the most relevant indicator of a GCS of 13 or less.