Every year the number of vehicles running on the road is increasing. these vehicles release many harmful gases into the atmosphere. what effect does this have on living things

It would be B.

Explanation:

A)Plants cannot complete the process of photosynthesis.  

B)It causes respiratory disorders in humans and animals.  

C)Microorganisms thrive under these conditions and grow in number.  

D)The gases mix with rain and add more nutrients to aquatic ecosystems.

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