Which is an example of a compound-complex sentence?

a. She has no children, and her sister, who has a history of hypertension and breast CA, is her only living sibling.
b. Despite some initial objections to anesthesia, he ultimately agreed to the procedure.
c. The patient presented with 3 days of nausea and vomiting and was admitted to the ER for rehydration and evaluation.
d. X-ray revealed scattered nodules in both lower lobes, confirming our original diagnosis.