Mario brings his hands near a fire and feels its warmth. If the air around Mario's fireplace is still, most of the heat is reaching his hands through .

Radiation

Explanation:

While being beside a campfire, the heat is transmitted by radiation from fire.  

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.