Harmful chemicals released directly into the atmosphere due to either human activities or natural processes are air pollutants.
a) primary
b) secondary
c) tertiary
d) quaternary

correct answer is a) primary air pollutants

Explanation:

solution

primary air pollutants material are that material which release pose health risk in the unmodified form and they emitted directly from identifiable source not react so they are primary air pollutant

and some major material released directly into the atmosphere as unmodified are given below

they all are primary air pollutants

so correct answer is is a) primary air pollutants

i believe the answer is c. "baking" is the gerund, while "baking blueberry muffins" would be the gerund phrase. hope this ! : )

the answer is barium and copper bromide