Final answer:
The correct needle for an IA nerve block is a long needle with a smaller gauge, used to accurately navigate to the mandibular foramen and deliver anesthetic with minimal trauma and deflection.
Step-by-step explanation:
For administering an Inferior Alveolar (IA) nerve block, the correct choice would be a long needle with a smaller gauge. The IA nerve block is a commonly used dental procedure that requires the needle to reach the mandibular foramen located near the mandibular ramus. To ensure appropriate depth and to navigate through the soft tissue without causing unnecessary trauma, a long needle (typically around 35 mm or 1.5 inches) is ideal. Additionally, a smaller gauge (usually 25 or 27 gauge) is preferable as it is less likely to deflect and can deliver the anesthetic agent more precisely.