Surgery A punch biopsy shows carcinoma rectum with fixed mass. X-ray chest normal, which of the following is LEAST useful investigation A Rigid protoscope B Barium enema C CT chest D MRI-abdomen and pelvis 💡 Explanation A punch biopsy shows carcinoma rectum with fixed mass. X-ray chest normal, which of the following is LEAST useful investigation ✓ Correct Answer: A. Rigid protoscope