**Core Concept**
Malignant gastric ulcers are a type of gastrointestinal malignancy characterized by uncontrolled cell growth and invasion of surrounding tissues. The characteristic feature of malignant gastric ulcers on Barium meal studies is a specific radiographic appearance that distinguishes them from benign ulcers.

**Why the Correct Answer is Right**
The characteristic feature of malignant gastric ulcers is the presence of an **infiltrative growth pattern**, which causes the ulcer to appear as a **ulcer with a narrow base and a wide rim** or a **polypoid mass**. This is due to the aggressive invasion of the tumor into the surrounding gastric wall, leading to a characteristic appearance on Barium meal studies. The narrow base and wide rim are due to the tumor's tendency to grow in a submucosal or serosal location, causing the ulcer to appear as a flat or polypoid mass.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because a benign ulcer typically has a wide base and a narrow rim, which is the opposite of the characteristic feature of malignant gastric ulcers.
* **Option B:** This option is incorrect because a duodenal ulcer is a different type of gastrointestinal lesion that is located in the duodenum, not the stomach.
* **Option C:** This option is incorrect because a gastric carcinoma may appear as a mass or an ulcer, but the characteristic feature of malignant gastric ulcers is the presence of an infiltrative growth pattern, which is not specified in this option.

**Clinical Pearl / High-Yield Fact**
A classic radiographic feature of malignant gastric ulcers is the presence of an **ulcer with a narrow base and a wide rim**, which is due to the tumor's tendency to grow in a submucosal or serosal location. This feature is often seen on Barium meal studies and is an important diagnostic clue for malignant gastric ulcers.

**Correct Answer:** C.