**Core Concept**
Fine-needle aspiration cytology (FNAC) is a diagnostic technique used to collect cell samples from superficial masses or lesions for histopathological examination. The choice of needle gauge is crucial in FNAC to ensure adequate sampling and minimize complications.

**Why the Correct Answer is Right**
The commonly used FNAC needle gauge ranges from 22 to 26, which provides a good balance between sampling adequacy and patient comfort. Needles with a gauge of 22-26 are thin enough to cause minimal discomfort and bleeding, yet thick enough to collect sufficient cell material for cytological examination. This range also reduces the risk of needle breakage and facilitates easy insertion and withdrawal from the tissue.

**Why Each Wrong Option is Incorrect**
**Option A:** Needles with a gauge of 26-29 are too thin and may not collect sufficient cell material, leading to inadequate sampling and potential false-negative results.
**Option C:** Needles with a gauge of 18-22 are thicker and may cause more discomfort and bleeding, making them less suitable for FNAC.
**Option D:** Needles with a gauge of 16-18 are too thick and may not be suitable for FNAC due to the increased risk of complications and inadequate sampling.

**Clinical Pearl / High-Yield Fact**
When performing FNAC, it's essential to use a needle with a gauge of 22-26 to ensure accurate sampling and minimize complications. Always choose the thinnest needle possible that still allows for adequate cell collection to reduce patient discomfort and risk of bleeding.

**✓ Correct Answer: B. 22-26**