Final answer:
Cholangiocarcinoma is a type of malignant neoplasm within the gallbladder.
Step-by-step explanation:
The correct answer is d) Cholangiocarcinoma. Cholangiocarcinoma refers to a malignant neoplasm within the gallbladder. It is a type of cancer that originates in the bile ducts. Unlike cholecystitis, which is inflammation of the gallbladder, hepatoma which is liver cancer, or cholelithiasis which is the presence of gallstones, cholangiocarcinoma specifically refers to gallbladder cancer.