A 2-year-old boy presented to the ER with stridor, shoness of breath and difficulty in swallowing. Patient also gave history of recurrent chest infections in the past for which the child was frequently hospitalized. Upper GI endoscopy was done and it was normal. Lab findings revealed normal studies. Chest x- ray All of the following are involved in the development of the structure causing the above condition except: -

This is a case of Dysphagia lusoria due to aberrant right subclan aery. Chest x ray shows superior mediastinum widening. Barium study shows revealed persistent, smooth indentation of the posterior aspect of the upper thoracic esophagus at T4 level, suggesting external compression. CT shows the aberrant right subclan aery compressing the posterior wall of esophagus. Aberrant right subclan aery develops from: - A. Caudal pa of right dorsal aoa B. Right 7th cervical intersegmental aery C. Right 4th arch