Step 1: Understanding air pollution data.
NEERI monitors air quality parameters in industrial regions of India to assess pollution levels. Step 2: Analyzing the options. (A) hydrocarbons: Incorrect. They are present but not the highest. (B) carbon monoxide: Incorrect. It is higher in traffic-dense areas. (C) suspended particulate matter: Incorrect. Though present, it is not the highest in this region. (D) sulphur di-oxide: Correct. Industrial activities in Chembur–Trombay release high levels of sulphur di-oxide. Step 3: Conclusion.
The correct answer is (D) sulphur di-oxide.