This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiration, Subject name: Pathology
Most common type of pneumoconiosis, associated with TB is? 
Select and explain. 
A. Silicosis, B. Bysinosis, C. Asbestosis, D. Baggassosis
A: Silicosis
Answer: A: Silicosis 
Explanation: Ans. is 'a' i.e., Silicosis * Silicosis is associated with an increased susceptibility to T.B. It is postulated that silicosis results in depression of cell mediated immunity and the crystalline silica may inhibit the ability of pulmonary macrophages to kill phagocytosed mycobacteria. Nodules of silicotuberculosis often display a central zone of caseation.