A patient present with dysphagia of 4 weeks duration. Now he is able to swallow liquid food only. Which of the following is the one investigation to be done

investigations of carcinoma oesophagus includes, Barium swallow: Shouldering sign and irregular filling defect. * Oesophagoscopy to see the lesion, extent and type. * Biopsy for histological type and confirmation. * Chest X-ray to look for aspiration pneumonia. * Bronchoscopy, to see an invasion in upper third growth. * Oesophageal endosonography, to look for the involvement of layers of oesophagus, nodes, cardia and left lobe of the liver. Nodes smaller than 5 mm can be very well visualised by EUS which may be missed in CT scan. EUS guided transmucosal nodal needle aspiration cytology can also be done. * CT scan, (95% accuracy) to look for a local extension, nodal status, perioesophageal/diaphragmatic/ pericardial (1%)/vascular infiltration, obliteration of mediastinal fat and status of the tracheo-bronchial tree in case of upper third growth. Ref: SRB&;s manual of surgery,3 rd ed, pg no 753