**Core Concept**
The question is testing the knowledge of the most common artery involved in bleeding from a duodenal ulcer. This is related to the anatomy of the duodenum and its blood supply. The duodenum receives its blood supply from branches of the gastroduodenal artery, which is a branch of the common hepatic artery.

**Why the Correct Answer is Right**
The correct answer is the gastroduodenal artery, specifically its right gastroepiploic branch. This branch is most commonly involved in bleeding from duodenal ulcers due to its close proximity to the duodenal wall and the high pressure of the arterial blood. The right gastroepiploic artery is a terminal branch of the gastroduodenal artery and supplies the right side of the greater curvature of the stomach and the first part of the duodenum.

**Why Each Wrong Option is Incorrect**
* **Option A:** The left gastric artery primarily supplies the stomach and is less likely to be involved in duodenal ulcer bleeding.
* **Option B:** The splenic artery primarily supplies the spleen and is not directly related to the blood supply of the duodenum.
* **Option C:** The superior mesenteric artery supplies the small intestine, but its branches are less likely to be involved in duodenal ulcer bleeding.

**Clinical Pearl / High-Yield Fact**
The "rule of fours" is a useful mnemonic for remembering the common sites of gastrointestinal bleeding: the first four letters of "Four Score and Seven Years Ago" correspond to the first four letters of "Forest, Stomach, Oesophagus, Rectum", which are the common sites of upper and lower GI bleeding.

**Correct Answer: B. Gastroduodenal artery.**