Answer: B. Endoscopy.
Because the patient is symptomatic, endoscopy is indicated.
A CT scan of the chest is useful for organic and inorganic materials.
A basic chest radiograph cannot reliably exclude a foreign body.
Barium swallow is difficult in pediatric patients, particularly this child, who is refusing oral fluids.
Water-soluble media risk pneumonitis if aspirated. Non–water-soluble materials risk increased inflammation if leakage occurs into the mediastinum. Barium may also obscure subsequent endoscopic visualization.