A 1-Week-Old Kid Is Brought to the ER with Poor

A 1-week-old kid is brought to the ER with poor eating, lethargy, and odd "muscle motions" involving the left thumb and hand during the previous two days. The patient's mother had adequate prenatal care, had a normal pregnancy, and did not use any drugs other than prenatal vitamins. The infant's vital signs are normal, but cuff blood pressure measurement reveals remarkable bending of the left wrist and thumb and extension of the fingers. A hypoplastic mandible, low-set ears, bifid uvula, and cleft palate are discovered during a physical examination. An x-ray of the chest shows reduced soft-tissue attenuation in the right anterior mediastinum. Which of the following embryonic structures is most likely affected by these findings?

A) Anterior neuropore
B) Foramen cecum
C) Rathke pouch
D) Second pharyngeal cleft
E) Third pharyngeal pouch