**Core Concept**
The management of gastric ulcers involves a combination of acid suppression and endoscopic evaluation to assess healing and rule out malignancy. Proton pump inhibitors (PPIs) are commonly used to reduce gastric acid secretion, facilitating ulcer healing.

**Why the Correct Answer is Right**
The American College of Gastroenterology recommends a repeat upper GI endoscopy 6-8 weeks after initiating PPI therapy to assess the healing of the gastric ulcer and evaluate for the presence of malignancy. This timeframe allows sufficient time for the ulcer to heal, but is early enough to catch any potential malignancy before it progresses. The mechanism of PPIs involves irreversible inhibition of the H+/K+ ATPase enzyme on the gastric parietal cell surface, reducing gastric acid secretion and promoting ulcer healing.

**Why Each Wrong Option is Incorrect**
**Option A:** 2 weeks is too early to assess healing, as PPI therapy may not have had sufficient time to take effect.
**Option B:** 4 weeks may still be premature, as some ulcers may not have fully healed, and malignancy may not be ruled out.
**Option D:** 12 weeks is excessively long, as prolonged PPI use may lead to complications such as osteoporosis and increased risk of fractures.

**Clinical Pearl / High-Yield Fact**
It's essential to note that a repeat endoscopy should be performed regardless of the patient's symptoms, as some gastric ulcers may not cause symptoms despite being malignant. This highlights the importance of a timely and thorough evaluation to rule out malignancy.

**✓ Correct Answer: C. 6 weeks**