**Core Concept**
Infantile hemangiomas are the most common benign tumors of infancy, characterized by **proliferating endothelial cells**. The treatment of infantile hemangiomas often involves **propranolol**, a **beta-blocker**.

**Why the Correct Answer is Right**
Propranolol has been shown to be effective in treating infantile hemangiomas by inducing **apoptosis** and inhibiting **angiogenesis**. The exact mechanism is not fully understood, but it is thought to involve the **downregulation of vascular endothelial growth factor (VEGF)**.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it is not a standard treatment for infantile hemangiomas.
**Option B:** Incorrect as it is not typically used for this condition.
**Option C:** Incorrect because, although used in some cases, it is not the first line of treatment.
**Option D:** Incorrect as it is not a recognized treatment for infantile hemangiomas.

**Clinical Pearl / High-Yield Fact**
Propranolol is now considered the first-line treatment for problematic infantile hemangiomas due to its efficacy and relatively safe side-effect profile.

**Correct Answer:** D. Propranolol.