If the price of petral is increased by 20% by what percentage should the consumption be decreased by the consumer if the expenditure on petrel remains unchanged?

If the price of petral is increased by 20% by what percentage should the consumption be decreased by the consumer if the expenditure on petrel remains unchanged?

A. 16 2/3%
B. 6 2/3%
C. 8%
D. 15%