Option D: A rubber balloon filled with hydrogen bursts when it goes up in the air because air pressure decreases. As the balloon ascends, it enters regions of lower atmospheric pressure. Inside the balloon, the pressure of the hydrogen gas remains relatively constant. However, the decreasing external air pressure exerts less force on the balloon’s surface. This pressure difference causes the hydrogen gas inside the balloon to expand to occupy a larger volume. Since the balloon’s elasticity has limits, it eventually reaches a point where it can no longer contain the expanding gas, leading to the balloon bursting.

Option A (the weight of hydrogen increases) is incorrect because the weight of the hydrogen remains constant. Option B (air pressure increases) is incorrect as the scenario involves a decrease in air pressure with altitude. Option C (the pressure of hydrogen decreases) is incorrect because the pressure of the hydrogen gas inside the balloon remains relatively constant; it’s the external air pressure that decreases. Therefore, the most accurate explanation is option D, as the bursting of the balloon is a result of the decreasing air pressure at higher altitudes.