which disorder is best characterized by excessive or unrealistic apprehension that causes physical symptoms, such as restlessness, fatigue, and muscle tension, and lasts for six months or longer?

This is the Generalized Anxiety Disorder or GAD by the initials. This disorder occurs when a person is constantly thinking about negative or bad things that can happen to him or nearby people, although these thoughts cause them much apprehension cannot stop them. This disorder is associated, in addition to the psychological symptoms, to various physical symptoms such as muscle tension.

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The answer for this question is c