**Core Concept**
The coeliac trunk is a major artery that arises from the abdominal aorta, supplying oxygenated blood to the foregut structures in the abdominal cavity. It divides into three main branches: left gastric, splenic, and common hepatic arteries.

**Why the Correct Answer is Right**
The right gastric artery, on the other hand, is a branch of the common hepatic artery, which in turn is a branch of the coeliac trunk. However, the right gastric artery itself is not a direct branch of the coeliac trunk. Instead, it arises from the common hepatic artery, which has already branched off from the coeliac trunk. This distinction is crucial in understanding the vascular anatomy of the abdominal cavity.

**Why Each Wrong Option is Incorrect**
**Option A:** The splenic artery is a direct branch of the coeliac trunk, which supplies blood to the spleen and the pancreatic tail.
**Option B:** The hepatic artery (common hepatic artery) is a direct branch of the coeliac trunk, which supplies blood to the liver and the pylorus.
**Option C:** The left gastric artery is a direct branch of the coeliac trunk, which supplies blood to the stomach.

**Clinical Pearl / High-Yield Fact**
It's essential to remember the three direct branches of the coeliac trunk: left gastric, splenic, and common hepatic arteries. These branches are critical for understanding the vascular supply of the foregut structures and for diagnosing and managing various abdominal pathologies.

**✓ Correct Answer:** D. Right gastric artery