Answer:
D. Oncologist
Step-by-step explanation:
A gynecologist specializes in the female reproductive system. An orthopedist deals with injuries of the muscular and skeletal system. A dermatologist specialize in the skin, hair and nails.
An oncologist is a doctor that diagnoses and treats cancer. Diana was just diagnosed with cancer, so she would be seeing an oncologist. Therefore, the correct answer is D. Oncologist.