Final answer:
The appropriate diagnostic test for the elderly patient with colon cancer who has difficulty moving is colonoscopy.
Step-by-step explanation:
The appropriate diagnostic test to perform first for the elderly patient with colon cancer who experiences difficulty in moving and requires assistance with turning and ambulating is a colonoscopy. Colonoscopy is the gold standard for the diagnosis of colorectal cancer.
It involves using a camera at the end of a long tube inserted into the colon to directly visualize the lining of the large intestine and identify any suspicious areas that may be cancerous or potentially pre-cancerous polyps. If polyps or cancerous lesions are found during the colonoscopy, they can be removed.