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
Which of the following type hypersensitivity reactions occurs in Farmer's lungs -a)  Type Ib)  Type IIc)  Type IIId)  Type IV 
Select and explain. 
A. ab, B. cd, C. bd, D. ac
B: cd
Answer: B: cd 
Explanation: Hypersensitivity pneumonitis (including farmer's lung) is an immunologically mediated response to an extrinsic antigen that involves both immune complex (type HI) and delayed type (type IV) hypersensitivity reactions._____ Robbins 703.