**Core Concept**
Cushing ulcer is a rare but serious complication of head trauma or intracranial hypertension, characterized by the formation of a gastric ulcer in the context of increased intracranial pressure. This phenomenon is attributed to the release of various stress hormones, including cortisol, which can alter the gastric mucosa's protective mechanisms.

**Why the Correct Answer is Right**
Cushing ulcer is a result of the body's response to stress, which leads to the release of cortisol and other stress hormones. These hormones cause vasoconstriction in the gastric mucosa, reducing blood flow and impairing the protective mechanisms of the stomach lining. This can lead to the formation of gastric ulcers, particularly in the setting of increased intracranial pressure.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Cushing ulcer is not typically associated with chronic conditions such as chronic obstructive pulmonary disease (COPD).
**Option B:** This option is incorrect because Cushing ulcer is not a direct consequence of the use of corticosteroids, although long-term steroid use can increase the risk of gastric ulcers.
**Option C:** This option is incorrect because Cushing ulcer is not typically seen in the context of peptic ulcer disease, which is a separate clinical entity.

**Clinical Pearl / High-Yield Fact**
Cushing ulcer is a classic example of a stress ulcer, which can be prevented or treated with the use of histamine-2 (H2) blockers or proton pump inhibitors (PPIs). It's essential to recognize the connection between increased intracranial pressure and the development of Cushing ulcer, particularly in the context of head trauma or brain tumors.

**Correct Answer:** D.