A) Incorrect. Blood tests do not directly visualize the inflamed appendix. They provide information about markers of infection and inflammation in the body.

B) Incorrect. While blood tests can support the diagnosis of appendicitis, they do not confirm it on their own. They provide additional information to aid in the diagnostic process.

C) Correct. Blood tests, specifically white blood cell count and C-reactive protein levels, provide valuable information about infection markers and inflammation in the body. Elevated levels may suggest the presence of an inflammatory process like appendicitis.

D) Incorrect. Blood tests are not primarily used to assess gastrointestinal motility. They are focused on assessing markers of infection and inflammation.