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: Microbiology
IFN-β is secreted by 
Select and explain. 
A. Leucocytes, B. Fibroblasts, C. Nk cells, D. Macrophage
B: Fibroblasts
Answer: B: Fibroblasts 
Explanation: IFN-α - Leucocytes.
IFN-β - Fibroblasts.
IFN-γ -  T4 and Tc cells, Nk cells.