Rising concerns about pollution in major Indian cities have led to a dramatic increase in sales of home air purifiers. New Delhi, which has been called the most polluted city in the world by the WHO, is not only the biggest buyer of air purifiers but is also the city that is seeing the fastest growth in sales of these devices.

Question: Air purifier is beneficial for those with allergies, asthma and other respiratory problems.
Options:
A. true, B. false, C. uncertain
Answer: "B"