This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Occupational Health, Subject name: Social & Preventive Medicine
Particle size which can easily go into the interior of lung and reache alveoli is: 
Select and explain. 
A. 0.5 - 3 im, B. 3-5 im, C. 5-10 im, D. 10-15 im
A: 0.5 - 3 im
Answer: A: 0.5 - 3 im 
Explanation: Ans: a (0.5-3 im) Ref: Park, 19th ed,p. 661Particle between 0.5-3 microns are the most dangerous because they reach the interior of the lungs with ease.