How does the norm height of a gas balloon with maximum differential pressure change by dropping ballast?

Question

Question Quiz BPL Gas - Balloon Pilot License - Principles of Flight (Balloon)

QuizVDS · Accepted Answer

It increases by 80 m when total mass is reduced by 1%

QuizVDS · Answer

It increases by 8 m when total mass is reduced by 10%.

QuizVDS · Answer

It decreases by 8 m when total mass is reduced by 10%.

QuizVDS · Answer

It decreases by 80 m when total mass is reduced by 1%.

Id 416 - BPL Gas - How does the norm height of a gas balloon with maximum differential pressure change by dropping ballast?