**Core Concept**
The treatment of choice for duodenal ulcer without complications such as hemorrhage involves managing the underlying pathophysiology of the condition, which is excessive acid production in the stomach. This is typically achieved through pharmacological means, specifically by inhibiting the final step in gastric acid secretion.

**Why the Correct Answer is Right**
Proton pump inhibitors (PPIs) work by irreversibly inhibiting the H+/K+ ATPase enzyme system at the secretory surface of gastric parietal cells. This enzyme is responsible for the final step in acid production, and its inhibition leads to a significant reduction in gastric acid secretion. PPIs have been shown to be highly effective in healing duodenal ulcers and preventing recurrence. They are generally well-tolerated and have a favorable safety profile, making them an ideal first-line treatment for uncomplicated duodenal ulcers.

**Why Each Wrong Option is Incorrect**
**Option A:** Highly selective vagotomy involves cutting the vagus nerve branches that supply the stomach, but it carries a higher risk of complications and is generally reserved for cases where medical therapy has failed. It is not the treatment of choice for uncomplicated duodenal ulcers.
**Option B:** Trunkal vagotomy involves cutting the main trunk of the vagus nerve, which can lead to significant side effects such as weight loss, diarrhea, and malabsorption. It is not a preferred treatment for uncomplicated duodenal ulcers.
**Option D:** Saying "None" is incorrect because PPIs are indeed a treatment option for duodenal ulcers.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that PPIs have a synergistic effect when combined with antibiotics in the treatment of Helicobacter pylori infection, which is a major cause of duodenal ulcers. This combination therapy is highly effective in eradicating the infection and preventing recurrence.

**✓ Correct Answer: C. Proton pump inhibitors**