A 63-year-old man complains of trouble swallowing and hoarseness. On physical exam, he is noted to have ptosis and a constricted pupil on the left, and a diminished gag reflex. Neurological examination shows decreased pain and temperature sensation on the left side of his face and on the right side of his body. Which of the following vessels is most likely occluded?
A. Anterior inferior cerebellar artery (AICA)
B. Anterior spinal artery
C. Middle cerebral artery (MCA)
D. Posterior cerebral artery (PCA)
E. Posterior inferior cerebellar artery (PICA)