**Core Concept**
The underlying principle being tested is the pathophysiology of neonatal jaundice, specifically the role of hemolysis due to blood group incompatibility between the mother and the baby. This condition is related to **hemolytic disease of the newborn (HDN)**, which occurs when there are antibodies against the baby's red blood cells in the mother's blood.

**Why the Correct Answer is Right**
Given the mother's blood group is 'O' -ve and the baby's is 'A' +ve, the most likely cause of jaundice in this scenario is **ABO incompatibility** or **Rh incompatibility**. However, since the mother is Rh-negative and the baby is Rh-positive, the scenario suggests an **Rh incompatibility** reaction, where the mother's immune system reacts to the Rh-positive red blood cells of the baby, leading to hemolysis.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because, although ABO incompatibility can cause jaundice, the primary concern with an 'O' negative mother and an 'A' positive baby would more directly suggest an Rh incompatibility issue due to the Rh-negative status of the mother.
**Option B:** Without specific details on this option, it's generally incorrect because the clinical presentation points towards an immune-mediated hemolysis rather than issues like infection or congenital anomalies.
**Option C:** Similarly, without specifics, this option would be incorrect as it does not align with the blood group incompatibility suggested by the scenario.
**Option D:** This option is incorrect as the details provided do not support a diagnosis that would be represented by this choice, assuming it does not relate to blood group incompatibility.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that **Rh incompatibility** occurs when an Rh-negative mother carries an Rh-positive fetus, which can lead to the production of anti-Rh antibodies in the mother, potentially causing hemolytic disease of the newborn. This condition can be prevented with **RhoGAM** administration to Rh-negative mothers during pregnancy.

**Correct Answer:** D. Hemolytic disease of newborn