This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Medicine
True about miliary tuberculosis 
Select and explain. 
A. Occurs following primary reactivation, B. Occurs following secondary reactivation, C. Both primary and secondary reactivation, D. All
D: All
Answer: D: All 
Explanation: Military TB is due to hematogenous spread of tubercle bacilli.Although in children,it is often the consequence of primary infection,in adults,it may be due to either recent infection or reactivation of old disseminated foci.The lesions are usually yellowish granulomas 1--2 mm in diameter that resemble millet seeds Reference: Davidson edition23rd pg 589