Malignant tumors are cancerous growths. They are often resistant to treatment, may spread to other parts of the body and they sometimes recur after they were removed.
Benign is not necessarily cancer because it doesn't spread the way a malignant tumor can. Malignant is a tumor made up of cancer cells, and a neoplasm is an abnormal growth of tissue as a characteristic of cancer.
I would have to agree with you! B is the correct answer because the doctor is disclosing that confidential information with the nurse that is not on the case.