Final answer:
The most suitable diagnostic method for evaluating a child who is worried or anxious would be a psychological assessment, which can offer insight into their emotional and psychological state.
Step-by-step explanation:
When evaluating a child who is worried or anxious, the most appropriate diagnostic method among the options provided would be a psychological assessment. Blood tests, X-rays and other imaging studies are not typically used to assess emotional or psychological conditions unless there is a suspicion of a physical illness that could be causing psychological symptoms. A psychological assessment can include various tools such as self-report inventories, projective tests, and personality assessments like the Minnesota Multiphasic Personality Inventory (MMPI) or the Myers-Briggs Type Indicator (MBTI). These assessments help in understanding the child's emotional state, thought patterns, and behavior, which are crucial for diagnosing and treating anxiety disorders.