D

Posterior fibers of the temporalis muscle pull the mandibible upward and backward, producing retrusion; masseter mainly elevates, and the pterygoids are prime protruders, not retractors. Electromyographic studies show higher activation of posterior temporalis than masseter during retrusion movements, confirming its key role in mandibular retraction [Blanksma & van Eijden, 1997, PMID 9042076].