“White elephant” means

The correct answer is B. A white elephant is a possession that is costly to keep and of little practical use to its owner. The idiom is traced to the kingdom of Siam (now Thailand), where white elephants were sacred and rare. A ruler could gift one to a courtier, who could not refuse it, and its upkeep was ruinously expensive.

Why the others fail:

• A is wrong because rarity is not the meaning. The idiom is about burden, not scarcity.
• C is wrong because a white elephant does exist. The point is that it is a costly liability.
• D is the opposite of the idiom's sense.

Core concept: idioms and vocabulary, which UPPSC tests in the language and comprehension sections. For Mains, the idea links to white elephant projects, such as underused infrastructure or loss-making public enterprises whose maintenance drains the exchequer. It also supports the case for cost-benefit appraisal before large capital outlays.

Trap: candidates pick A because the word white suggests something rare or special. Read the idiom as a burden, not a prize.