**Core Concept**
The child's presentation of congenital hypocalcemia, seizures, and tetany, along with the described facial features, suggests a diagnosis of **DiGeorge Syndrome**. This condition is characterized by a complex of congenital anomalies, including thymic hypoplasia, parathyroid gland aplasia, and cardiac defects.

**Why the Correct Answer is Right**
DiGeorge Syndrome is associated with aplasia or hypoplasia of the **thymus gland**. The thymus plays a crucial role in the development of the immune system, particularly in the maturation of T-lymphocytes. The absence or underdevelopment of the thymus can lead to severe immunodeficiency. The condition is also characterized by hypoparathyroidism, resulting from the aplasia or hypoplasia of the parathyroid glands, which are essential for regulating calcium levels in the body.

**Why Each Wrong Option is Incorrect**
* **Option A:** The pancreas is not directly associated with the child's symptoms or the underlying condition of DiGeorge Syndrome.
* **Option B:** The adrenal glands can be affected in DiGeorge Syndrome, but the primary issue is not aplasia or hypoplasia of these organs.
* **Option D:** The small intestine is not directly related to the child's condition or symptoms.

**Clinical Pearl / High-Yield Fact**
DiGeorge Syndrome is a classic example of a condition that presents with a complex of congenital anomalies, including thymic hypoplasia, parathyroid gland aplasia, and cardiac defects. It is essential to consider this diagnosis in newborns with congenital hypocalcemia, seizures, and tetany, along with characteristic facial features.

**Correct Answer:** C.