This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pneumonia, Subject name: Medicine
Recurrent aspiration pneumonia is caused by: 
Select and explain. 
A. Dermatomyositis/polymyositis, B. Rheumatoid ahritis, C. Progressive systemic sclerosis, D. Systemic lupus erythematosus
C: Progressive systemic sclerosis
Answer: C: Progressive systemic sclerosis 
Explanation: Systemic sclerosis is characterized by fibrosis of lower esophageal sphincter | Leading to decrease in tone of LES | Resultant GERD | Leads to Recurrent Aspiration Pneumonia