**Core Concept**
The repair of a unilateral cleft lip is a surgical procedure that aims to restore the normal anatomy and function of the lip. The timing of the repair is crucial to minimize scarring and maximize cosmetic and functional outcomes. The procedure involves the reconstruction of the **orbicularis oris muscle** and the repair of the **cleft** in the lip.

**Why the Correct Answer is Right**
The best time for repairing a unilateral cleft lip is typically around 3-6 months of age. This timing allows for the **healing** of the wound to occur before the child starts to crawl and become more active, reducing the risk of complications. The **Millard rotation-advancement repair** is a common technique used for this procedure.

**Why Each Wrong Option is Incorrect**
**Option A:** Is incorrect because it is too early, and the baby may not be physically ready for the surgery.
**Option B:** Is not a standard option for cleft lip repair.
**Option D:** Is too late, as early repair can help with **speech development** and reduce the risk of **hearing problems**.

**Clinical Pearl / High-Yield Fact**
The key to a successful cleft lip repair is to restore the **anatomical continuity** of the **orbicularis oris muscle**, which is essential for normal lip function and cosmetics.

**Correct Answer:** C. 3-6 months