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: Medicine
The test is used for: 
Select and explain. 
A. Tuberculosis, B. Syphilis, C. Sarcoidosis, D. Hepatitis B
A: Tuberculosis
Answer: A: Tuberculosis 
Explanation: The principles of interferon-gamma release assays (IGRAs). A sample of either (A) puriﬁed T cells (T- SPOT TB test) or (B) whole blood (QuantiFERON–TB Gold test) is incubated in the presence of antigens speciﬁc to Mycobacterium tuberculosis (MTB). The release of interferon-gamma (IFN-γ) by the cells is measured by enzyme-linked immunosorbent assay (ELISA). (ELISPOT = enzyme-linked immunosorbent spot assay).
Ref: Davidson Ed 22nd Pg 695