Hello!
To start, a pathogen is a virus that will cause disease. This question is referring to an airborne spread of pathogens.
Lung cancer is not a spreadable disease, so it is not the answer.
Lyme disease is caused by ticks, but they do not fly and spread their disease, so it is not the answer.
The flu is a disease caused by a bacteria. This bacteria is not airborne though. It is spread usually through physical contact.
Malaria is spread by mosquitos which will fly around and pass on the disease. The spread their disease through airborne transmission of malaria.
The answer is A. Malaria.
Hope this helped!