**Core Concept**
Nuchal translucency (NT) measurement is a critical component of first-trimester screening for fetal aneuploidy and other congenital anomalies. It involves the assessment of the thickness of the subcutaneous tissue at the back of the fetal neck between 11 and 14 weeks of gestation.

**Why the Correct Answer is Right**
Correct NT measurement is crucial for accurate screening results. The guidelines for NT measurement emphasize the importance of using a transvaginal ultrasound probe, as it provides a more accurate measurement than a transabdominal probe. Additionally, the measurement should be taken at the correct gestational age, between 11 and 14 weeks, and the fetal position should be optimized to ensure an accurate measurement.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because the use of a transvaginal probe is a requirement for accurate NT measurement.
**Option B:** Incorrect because the measurement should be taken between 11 and 14 weeks of gestation, and not beyond 14 weeks.
**Option C:** Incorrect because the use of a transabdominal probe is not recommended for NT measurement due to its lower accuracy compared to transvaginal ultrasound.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that NT measurement is just one component of the first-trimester screening, and other markers such as nuchal fold and nasal bone absence should also be assessed for accurate diagnosis.

**Correct Answer: C.** Transabdominal probe is not recommended for nuchal translucency measurement.