This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Regarding severe combined immunodeficiency disease ,which of the following statement is true 
Select and explain. 
A. Adenosine deaminase deficiency, B. Decreased circulating lymphocytes, C. NADPH oxidase deficiency, D. C1 esterase deficiency
A: Adenosine deaminase deficiency
Answer: A: Adenosine deaminase deficiency 
Explanation: Ref Robbins 8/e p234;9/e p239 SCID represent a constellation of genetically distinct syndrome, all having in common defect in both humoral and cell mediated immune response