The correct answer is c. common bile duct.
Explanation: The term ‘choledoch’ comes from the Greek words ‘chole’ meaning bile and ‘doch’ meaning to lead or carry. Therefore, ‘choledoch’ refers specifically to the common bile duct, which is a vital tube in the digestive system that carries bile from the liver and gallbladder to the duodenum. Understanding medical terminology like this can help in comprehending various functions and conditions related to the liver and digestion.