Assertion: A hydrogen filled balloon stops using after it has attained a certain height in the sky.Reason: The atmospheric pressure decreases with height and becomes zero when maximum height is attained.

• A. Both assertion and reason are true and the reason is the correct explanation of the assertion
• B. Both assertion and reason are true but the reason is not the correct explanation of the assertion
• C. Assertion is true but the reason is false
• D. Assertion and reason is false