Answer:
increasing the temperature of the balloon
Explanation:
If you increase the temperature of the gas in the balloon, the pressure will initially increase. The balloon will expand until the pressure inside drops back down and is equal to the pressure outside.
If you increase the atmospheric pressure, the balloon will compress until the pressure inside equals the new pressure outside.
If you remove gas from the balloon, the pressure will drop, causing the balloon to compress until the pressure is again equal to the pressure outside.
if you place the balloon under water, it will be under greater pressure, causing the balloon to compress until the inside pressure equals the new outside pressure.
