"Puissant" is a formal, somewhat literary word that means having great power, strength, or influence, often used for rulers, armies, or nations. The question asks which option carries this sense of power.
Only "Powerful" captures the meaning of great strength and influence carried by puissant.
Let's summarize:
So the correct answer is "Powerful."
If the price of a commodity increases by 25%, by what percentage should the consumption be reduced to keep the expenditure the same?