Why does air in a room rise when it gains thermal energy from a heater? (1 point)
• Its molecules move around more quickly, so there is more space between them, making it less dense than the air above it.
• Its molecules move around more slowly, so there is more space between them, making it less dense than the air above it.
• Warm air always rises.
• Its molecules move around more quickly, so there is more space between them, reducing its mass.