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
A truck driver has chronic cough with fever since one month. Chest x-ray show bilateral reticulonodular infiltrates in mid and lower zones. Which of the following is possible diagnosis? 
Select and explain. 
A. Tuberculosis, B. ILD, C. Pneumococcal pneumonia, D. Pneumocystis carini pneumonia
D: Pneumocystis carini pneumonia
Answer: D: Pneumocystis carini pneumonia 
Explanation: Patients with Pneumocystis pneumonia develop dyspnoea,fever,and non productive cough.The classic findings on chest radiography consist of bilateral diffuse infiltrates beginning in the perihilar regions,but various atypical manifestations(nodular densities,cavitary lesions) have also been repoed.HRCT shows groundglass opacities in earlier stage. Reference:Harrison's medicine-18th edition,page no:1671.