**Core Concept**
The question is testing the identification of signs of a specific condition during autopsy in a fetus born dead at 5 months. The underlying principle involves the recognition of morphological changes that occur due to the condition.

**Why the Correct Answer is Right**
The correct answer is related to the signs of anemia in the fetus. Anemia in the fetus can lead to changes in the bone marrow, liver, and spleen. In the case of a fetus born dead, these changes can be identifiable during autopsy. The bone marrow may show erythroid hyperplasia, the liver may show extramedullary hematopoiesis, and the spleen may show congestion and fibrosis. These changes are indicative of anemia and can be identified during autopsy.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not relate to the signs of anemia in the fetus. The signs of infection, such as abscesses or granulomatous inflammation, may not be identifiable in a fetus born dead due to the lack of a functioning immune system.

**Option B:** This option is incorrect because it does not relate to the signs of anemia in the fetus. The signs of chromosomal abnormalities, such as trisomy 21, may be identifiable through genetic testing, but they may not be apparent during autopsy in a fetus born dead.

**Option C:** This option is incorrect because it does not relate to the signs of anemia in the fetus. The signs of congenital infections, such as syphilis or toxoplasmosis, may be identifiable through serological testing, but they may not be apparent during autopsy in a fetus born dead.

**Clinical Pearl / High-Yield Fact**
The signs of anemia in the fetus can be identified during autopsy through the examination of the bone marrow, liver, and spleen. This is an important consideration in cases of fetal demise at 5 months, as it can provide valuable information about the cause of death.

**Correct Answer:** D.