Final answer:
Dysphagia can be caused by Parkinson's disease, esophageal cancer, and stroke, but not by diabetes. It is characterized by difficulty or discomfort in swallowing.
Step-by-step explanation:
Dysphagia is the difficulty or discomfort in swallowing. It can be caused by various medical conditions, but it is not caused by diabetes. Dysphagia can be caused by Parkinson's disease, esophageal cancer, and stroke. Parkinson's disease affects the muscles in the mouth and throat, leading to swallowing difficulties. Esophageal cancer can create blockages or narrowings in the esophagus, making it hard to swallow. Additionally, a stroke can damage the brain's control over swallowing muscles.