Answer the following question given this paragraph: The density of air varies from place to place. Air density depends on several factors. One is temperature. Like other materials, warm air is less dense than cool air. Since warmer molecules have more energy, they are more active. The molecules bounce off each other and spread apart. Another factor that affects the density of air is altitude. Q: Since warmer molecules have more energy, they are more what? Choices: - inactive - dense - abundant - active A:
active