**Core Concept:**
The question involves a neonate presenting with abdominal distension and rectal bleeding, following a recent recovery from acute respiratory infection. These symptoms could indicate a gastrointestinal (GI) problem due to an immune system immaturity in premature infants.

**Why the Correct Answer is Right:**
In this case, the correct answer is **C.** Hemolytic-uremic syndrome (HUS), also known as thrombotic thrombocytopenic purpura (TTP), is a rare but severe condition in premature infants. It is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. The exact cause is a deficiency in ADAMTS13 (a protease that cleaves von Willebrand factor multimers) leading to unregulated activation of Von Willebrand factor and platelet aggregation.

**Why Each Wrong Option is Incorrect:**
A. Viral gastroenteritis is unlikely as it would usually present with acute onset of symptoms, rather than following a recovery from respiratory infection.
B. Meckel's diverticulum is a congenital abnormality, not related to recent infections or immune system immaturity.
D. Gastrointestinal atresia is a congenital anomaly, unrelated to recent infections or immune system immaturity.

**Why Option C is Right:**
Hemolytic-uremic syndrome is a result of a compromised immune system in premature infants, which leads to unregulated activation of Von Willebrand factor and platelet aggregation. This condition is triggered by a recent infection (in this case, respiratory infection) causing a transient immunosuppression, allowing a previously asymptomatic ADAMTS13 deficiency to become clinically significant.

**Clinical Pearl:**
Hemolytic-uremic syndrome in neonates is a critical condition that requires prompt recognition and management. Early diagnosis and treatment with plasma exchange and/or steroids can significantly improve outcomes.