**Core Concept**
Traction force required for forceps delivery in primigravida is a critical parameter in obstetrics, as excessive force can lead to fetal injury or maternal trauma, while inadequate force may result in failed delivery. The traction force should be sufficient to overcome the resistance offered by the fetal head and the pelvic floor.

**Why the Correct Answer is Right**
The traction force required for forceps delivery in primigravida is typically around 70-80 g, as recommended by the American College of Obstetricians and Gynecologists (ACOG). This force is sufficient to overcome the resistance offered by the fetal head and the pelvic floor, allowing for a safe and successful delivery. The traction force should be applied gently and progressively, allowing for adequate relaxation of the pelvic floor muscles.

**Why Each Wrong Option is Incorrect**
**Option A:** 50 g - This force is too low and may result in failed delivery, as it may not be sufficient to overcome the resistance offered by the fetal head and the pelvic floor.
**Option B:** 100 g - This force is too high and may result in fetal injury or maternal trauma, as it may cause excessive pressure on the fetal head and the pelvic floor.
**Option C:** 120 g - This force is even higher than Option B and may cause significant damage to the fetal head and the pelvic floor, making it an inappropriate choice.

**Clinical Pearl / High-Yield Fact**
When performing forceps delivery, it is essential to maintain a gentle and progressive traction force, allowing for adequate relaxation of the pelvic floor muscles. Excessive force should be avoided, as it may lead to fetal injury or maternal trauma.

**Correct Answer:** C. 80 g