This question checks the meaning of the phrase "cost an arm and a leg", which people use for something that is extremely expensive, so costly that it feels like giving up something very valuable to pay for it.
The correct option is "Exorbitant", since the phrase describes a price so high that paying it feels like a huge sacrifice.
Let's summarize:
So the option that best expresses the meaning of "cost an arm and a leg" is "Exorbitant".
If the price of a commodity increases by 25%, by what percentage should the consumption be reduced to keep the expenditure the same?