The correct answer is B: Very expensive. The idiom "cost an arm and a leg" is used to describe something that is extremely expensive, requiring a significant amount of money or a great sacrifice to obtain. It conveys the idea that the price is so high it's comparable to losing valuable body parts, emphasizing the immense cost involved. The origin of this idiom is often linked to the sacrifices made during wars, where soldiers might lose limbs, or to the high cost of commissioning portraits where the subject's arms and legs were included, making them more expensive than head-and-shoulder portraits.
For example, "That new sports car must have cost him an arm and a leg." Or, "Renovating our entire house is going to cost an arm and a leg."
Let's consider why the other options are incorrect:
- A: Cheap is the direct opposite of the idiom's meaning.
- C: Free and D: Reasonable also contradict the core meaning of being extremely costly.
Understanding such vivid idioms helps in grasping the nuances of English expressions.