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
A 35 year old lady complains dysphagia, Raynaud's phenomenon, sclerodactyly. Investigations show antinuclear antibody. The likely diagnosis is ? 
Select and explain. 
A. Systemic lupus erythematosis, B. Systemic sclerosis, C. Mixed connective tissue disorder, D. Rheumatoid ahritis
B: Systemic sclerosis
Answer: B: Systemic sclerosis 
Explanation: Ans. is 'b' i.e., Systemic sclerosiso Dysphagia, Raynaud's phenomenon, sclerodactyly in 35 years old lady suggest the diagnosis of systemic sclerosis (see above explanations).I think option 'b' needs some explanation here.Mixed connective tissue diseaseo Patients having the co-existence of features suggestive of SLE, polymyositis, Rheumatoid ahritis and systemic sclerosis.