The AQI of Delhi in December 2020 was 331. AQI denotes which of the following?

Correct option is C

The correct answer is Air Quality Index.
Air Quality Index
The National Air Quality Index (AQI) in India was launched on 17 September 2014 in New Delhi under the Swachh Bharat Abhiyan by Environment Minister Shri Prakash Javadekar. The air quality index is composed of 8 pollutants - PM10, PM2.5, NO2, SO2, CO, 03, NH3, and Pb). The Air Quality Index measures the quality of air. It shows the amount and types of gases dissolved in the air. There are 6 categories of air that have been created in this air quality index. These categories are based on air quality. These categories are; good, satisfactory, moderate, poor, very poor, and severe. As the air quality deteriorates, so does the ranking of air from good to bad than very poor to severe.