Correct Option: A

Endoscopymeans looking inside and typically refers to looking inside the body for medical reasons using an endoscope, an instrument used to examine the interior of a hollow organ or cavity of the body. Unlike most other medical imaging devices, endoscopes are inserted directly into the organ. Endoscopy can also refer to using a borescope in technical situations where direct line of-sight observation is not feasible. The following conditions and illnesses are most commonly investigated or diagnosed with an endoscopy: breathing disorders; chronic diarrhea; internal bleeding; irritable bowel syndrome; stomach ulcers, etc.