The answer is (d): a neurologic exam.
Explanation for each option:
a. A CBC (Complete Blood Count) is a blood test used to evaluate overall health and detect a variety of disorders, such as anemia, infection, and many other diseases. It is not typically used to diagnose degenerative disk disease.
b. A spinal tap, or lumbar puncture, involves collecting cerebrospinal fluid for testing. It is generally used to diagnose conditions affecting the brain and spinal cord, such as infections or bleeding, but not specifically for degenerative disk disease.
c. A myelogram is an imaging test that uses a contrast dye and X-rays or CT scans to look for problems in the spinal canal, including herniated disks or spinal stenosis. While it can be used to assess spinal issues, it is not the primary diagnostic tool for degenerative disk disease.
d. A neurologic exam is a comprehensive assessment of the nervous system and is often used to diagnose degenerative disk disease. It helps evaluate the function of the spinal cord and nerves, which can be affected by degenerative changes in the spine.
In summary, a neurologic exam is a key component in diagnosing degenerative disk disease, making option (d) the correct answer.