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
Conglomerate nodules in X-ray are seen in 
Select and explain. 
A. Sarcoidosis, B. Hypersensitive Pneumonitis, C. Silicosis, D. Lobar pneumonia
C: Silicosis
Answer: C: Silicosis 
Explanation: In silicosis long term less intense exposure, small rounded opacities in the upper lobes may appear in chest radiograph after 15-20years exposure. The nodular fibrosis may be progressive and coalesce and form nonsegmental conglomerate masses which are irregular and >1cm in diameter and can lead to progressive massive fibrosis.Reference: Harrison&;s Principles of Internal Medicine; 19th edition; Chapter 311; Occupational and Environmental Lung Disease