**Core Concept**
The likely diagnosis in this case involves a condition where blood escapes from the esophagus, leading to massive hematemesis. This condition is often associated with portal hypertension, which can cause dilation and stretching of the veins in the esophagus, leading to varices.

**Why the Correct Answer is Right**
The presence of moderate splenomegaly in Rahul suggests portal hypertension, which is a common cause of oesophageal varices. The history of fever treated with drugs could imply the use of non-steroidal anti-inflammatory drugs (NSAIDs), which are known to cause gastric ulcers but are less likely to cause massive hematemesis. The acute presentation of massive hematemesis in the context of recent fever and splenomegaly is more suggestive of an underlying condition causing portal hypertension, such as liver disease or portal vein thrombosis, leading to oesophageal varices.

**Why Each Wrong Option is Incorrect**
**Option A:** Drug-induced gastritis is unlikely to cause massive hematemesis, as it typically presents with epigastric pain and bleeding that is often self-limiting.
**Option B:** Oesophageal tear is a possibility in the context of a recent history of fever and vomiting, but it would be less likely to cause massive hematemesis without a preceding history of trauma or intubation.
**Option C:** Bleeding duodenal ulcer is a possible cause of hematemesis, but the presence of splenomegaly and recent fever suggests a more complex underlying condition, making this option less likely.

**Clinical Pearl / High-Yield Fact**
The presence of splenomegaly in a patient with acute hematemesis should prompt consideration of portal hypertension and oesophageal varices as a possible diagnosis.

**Correct Answer:**
✓ Correct Answer: D. Oesophageal varices