**Core Concept**
SNA (Sella-Nasion-A point) is a key cephalometric angle that evaluates the positional relationship of the maxilla relative to the cranial base. It is used to assess maxillary growth and skeletal development in orthodontic and maxillofacial analysis.

**Why the Correct Answer is Right**
SNA angle is formed by the line from the sella turcica (sella) to the nasion (N) and the line from nasion to the A-point (anterior point of the maxillary alveolar process). This angle directly reflects the position of the maxilla in relation to the cranial base. A higher SNA angle indicates a more upright maxilla (maxillary growth), while a lower angle suggests maxillary hypoplasia. It is a standard measure in diagnosing skeletal discrepancies like Class II or Class III malocclusion.

**Why Each Wrong Option is Incorrect**
Option A: The mandible’s position relative to the cranial base is assessed by SNB (Sella-Nasion-B point), not SNA.
Option C: Maxillo-mandibular relationship is evaluated using angles like Mandibular Plane Angle or the Mandibular Plane to the cranial base, not SNA.
Option D: SNA specifically measures maxilla-to-cranial base relationship, so this option is factually incorrect.

**Clinical Pearl / High-Yield Fact**
SNA is one of the most commonly used cephalometric angles in orthodontic diagnosis—remember: **SNA = Maxilla**, **SNB = Mandible**, and **ANB = Maxilla-Mandible relationship**.

✓ Correct Answer: B. Position of maxilla in relation to cranial base