**Core Concept**
Bone marrow biopsy is a crucial diagnostic tool for assessing hematological disorders in infants and children. It involves the sampling of bone marrow tissue to evaluate cellularity, morphology, and cytogenetic abnormalities. In infants, the iliac crest is a common site for bone marrow aspiration due to its accessibility and relatively smaller size compared to adults.

**Why the Correct Answer is Right**
The iliac crest is a suitable site for bone marrow biopsy in infants because it is a flat, broad surface that can be easily accessed. The iliac crest is located at the posterior superior iliac spine (PSIS), which is a palpable landmark that can be used as a reference point for the procedure. In infants, the iliac crest is relatively flat and has a smaller diameter compared to adults, making it an ideal site for bone marrow aspiration. The procedure typically involves a needle aspiration of the bone marrow, which is then examined for various parameters such as cellularity, morphology, and cytogenetic abnormalities.

**Why Each Wrong Option is Incorrect**
* **Option A:** The sternum is not a suitable site for bone marrow biopsy in infants due to its smaller size and location in the anterior chest wall, making it more difficult to access.
* **Option B:** The lumbar vertebrae are not typically used for bone marrow biopsy in infants due to their smaller size and the risk of spinal cord injury.
* **Option C:** The femoral head is not a common site for bone marrow biopsy in infants due to its smaller size and the risk of femoral neck fractures.

**Clinical Pearl / High-Yield Fact**
In pediatric patients, the iliac crest is a preferred site for bone marrow biopsy due to its accessibility and relatively smaller size, making it an ideal location for diagnostic and therapeutic procedures.

**Correct Answer: C. The femoral head is not a common site for bone marrow biopsy in infants due to its smaller size and the risk of femoral neck fractures.