Final answer:
The drain inserted during a cholecystostomy is the T-tube, which helps divert bile flow out of the body to promote healing. Other types like Robinson, Malecot, and Penrose serve different purposes and are not used for cholecystostomies.
Step-by-step explanation:
The type of drain that is inserted during a cholecystostomy is the T-tube drain. A cholecystostomy involves the gallbladder, which is a muscular sac that stores and concentrates bile. The T-tube is named for its shape, resembling the letter 'T,' and it is typically used after procedures which require bile to flow from the gallbladder to be diverted out of the body for drainage, thereby preventing bile leaks and promoting healing. This contrasts with the purposes of other types of drains, such as the Robinson (which is a simple, straight drainage tube), the Malecot (which has wings for retention in cavities), and the Penrose (which is a flat, drain used primarily for draining abscesses or surgical sites). Therefore, the correct answer is D. T-tube.