Step 1: Health knowledge.
Air pollution plus smoking aggravate allergic conditions.
Step 2: Remove diseases.
Pneumonia/diabetes/cancer are illnesses, not co-risk environmental factors here.
Step 3: Conclusion.
Hence (D) pollution.
“One of these days you’re going to talk yourself into a load of trouble,” her father said aggressively. What do you learn about Sophie’s father from these lines? (Going Places)