This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Anti U1 RNP is a feature of: 
Select and explain. 
A. SLE, B. MCTD, C. Sclerorema, D. CREST
B: MCTD
Answer: B: MCTD 
Explanation: MCTD