Which symptom is characterized by involuntary shaking or trembling of the body?

The symptom characterized by involuntary shaking or trembling of the body is body tremors. This condition can manifest in various forms and can be caused by a wide range of factors, including neurological disorders, anxiety, or the effects of certain medications or substances. Body tremors occur when muscles contract and relax rapidly, which results in the shaking motion.

In contrast, the other symptoms listed—loss of appetite, insomnia, and elevated mood—are not associated with physical trembling. Loss of appetite pertains to a decrease in desire to eat, insomnia refers to difficulty falling or staying asleep, and elevated mood typically involves an increase in feelings of happiness or euphoria, often seen in conditions such as mania or hypomania. These symptoms do not involve the involuntary muscle movements that are characteristic of body tremors.