Answer:
A. A chemical agent that can cause an illness.
Step-by-step explanation:
Second-hand smoke is a combination of smoke from the burning end of a cigarette and the smoke exhaled by the smoker. It contains more than 7,000 chemicals, including hundreds that are toxic and about 70 that can cause cancer.
Exposure to second-hand smoke can lead to various health problems, including lung cancer, heart disease, and respiratory infections. It is a significant health hazard, particularly for children and non-smoking adults who are regularly exposed to it in homes, workplaces, and public spaces.