**Core Concept**
The porta hepatis is a region in the liver where the hepatic artery, portal vein, and bile duct converge. This area is crucial for the delivery of oxygenated blood, nutrients, and bile to the liver parenchyma. The correct order of structures in the porta hepatis is essential for understanding liver anatomy and its clinical implications.

**Why the Correct Answer is Right**
The correct order of structures in the porta hepatis is as follows: the hepatic artery proper is posterior, followed by the portal vein, and finally the common bile duct. This order is based on the embryological development of the bile ducts, which arise from the foregut and eventually fuse to form the common bile duct. The hepatic artery proper, on the other hand, is a branch of the common hepatic artery that arises from the celiac trunk. The portal vein is formed by the confluence of the superior mesenteric and splenic veins. The common bile duct, formed by the junction of the cystic duct and the common hepatic duct, is the most anterior structure in the porta hepatis.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify the correct order of structures in the porta hepatis.
* **Option B:** This option is incorrect because it reverses the order of the hepatic artery and portal vein.
* **Option C:** This option is incorrect because it incorrectly places the common bile duct anterior to the portal vein.

**Clinical Pearl / High-Yield Fact**
Remember the acronym "HVBC" to recall the correct order of structures in the porta hepatis: Hepatic Vein (not mentioned in the options, but a useful mnemonic), Vascular (portal vein), Bile (common bile duct), and Celiac (hepatic artery proper).

**Correct Answer:** D.