**Core Concept**
Z plasty is a surgical technique used to lengthen a scar, improve its appearance, or reorient its direction. The goal of Z plasty is to increase the length of the scar while preserving its blood supply, minimizing the risk of complications.

**Why the Correct Answer is Right**
The lengthening of a scar is directly related to the angle of the Z plasty. A greater angle between the limbs of the Z plasty allows for more effective scar lengthening. This is because the increased angle enables the surgeon to incorporate more tissue into the new scar, thereby increasing its length. The ideal angle for maximum lengthening is between 60° to 120°.

**Why Each Wrong Option is Incorrect**
**Option A:** An angle of 30° would result in minimal lengthening, as it doesn't allow for significant incorporation of new tissue into the scar.

**Option B:** An angle of 180° would result in a large, potentially unstable flap, which may increase the risk of complications and doesn't necessarily provide additional lengthening benefits.

**Option C:** An angle of 45° is less effective for lengthening compared to the ideal range of 60° to 120°, as it doesn't allow for sufficient incorporation of new tissue.

**Clinical Pearl / High-Yield Fact**
When performing Z plasty, it's essential to maintain a balance between lengthening the scar and preserving its blood supply. A general rule of thumb is to keep the length of the limb of the Z plasty to a maximum of 2-3 times the width of the scar.

**Correct Answer:** C. 120° provides the maximum lengthening benefits due to the incorporation of more tissue into the new scar.