**Core Concept**
Failure to pass meconium within 48 hours of birth is a clinical indicator of an underlying intestinal obstruction or Hirschsprung's disease. This condition is characterized by the absence of ganglion cells in the distal colon, leading to a functional obstruction.

**Why the Correct Answer is Right**
Hirschsprung's disease is a congenital condition that affects the development of the enteric nervous system. The absence of ganglion cells in the affected segment of the colon leads to an accumulation of feces, resulting in a functional obstruction. This condition typically presents with failure to pass meconium within 48 hours of birth, abdominal distension, and bilious vomiting. The correct diagnosis is often confirmed by rectal biopsy, which shows the absence of ganglion cells.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the clinical scenario described. A history of maternal diabetes is associated with various congenital anomalies, but it is not directly related to failure to pass meconium.

**Option B:** While intestinal obstruction is a possible cause of failure to pass meconium, it is a broader term that encompasses various conditions, including Hirschsprung's disease. However, the question specifically asks for the suspicion of a particular condition.

**Option C:** This option is incorrect because it is not directly related to the clinical scenario described. A history of maternal exposure to teratogenic agents is associated with various congenital anomalies, but it is not specifically related to failure to pass meconium.

**Clinical Pearl / High-Yield Fact**
One important clinical pearl is that a rectal examination in a newborn with failure to pass meconium may reveal a tight anal sphincter, which is a characteristic finding in Hirschsprung's disease.

**Correct Answer: C. Hirschsprung's disease.**