Answer : stomach to the liver
The right option is A. hydrofluorocarbons
Hydrofluorocarbons are pollutants that are likely to be produced from air conditioning.
Hydrofluorocarbons (HFCs) are synthetic fluorinated strong greenhouse gases that are strongly accumulating in the atmosphere. Hydrofluorocarbons are mainly used as refrigerants. Hydrofluorocarbons are used to replace ozone depleting substances such as chlorofluorocarbons and hydrochlorofluorocarbons which are being phased out in air conditioning, refrigeration, foam blowing agents, and solvents. Hydrofluorocarbons are responsible for about 20% of climate pollution by 2050
Cell-tissue-organ-organ system-organism
I believe the correct answer is a. mutations.