You can carry out a test ,
1- take a sample of the air in a test tube
2-add limewater to the test tube
3- result : if it turns milky/cloudy it has microorganisms
4- reason: because every microorganism respires , and so it produces Carbon dioxide .
and limewater is the test to show the presence of Carbon dioxide .
I’m not sure but I’m guessing the answer would be the first one !
Please state the options / choices so that we can answer your question. Thank you.
Ummm ... true , but im pretty sure.