Ans: b) An efficient market

Market efficiency refers to the degree to which market prices reflect all available information. An efficient market is one where all information is already incorporated into prices, and so there is no opportunity to make profit as all such possibilities are eliminated instantaneously. Say a good is sold at $20 in market A, and at $30 in market B. Clearly there is an opportunity of making profit by buying in market A and selling in market B. However, if the market is efficient, this information is instantaneously available to everyone, and the two markets will fix a single price to prevent profit opportunities.

A Laissez-faire market is a free market, where supply and demand govern prices, and there are interventions like taxes or subsidies.

A socialist market involves public(government) or social ownership of goods, and their production may or may not be in a free way, i.e. it could be regularized.

A capitalist market is one where goods are owned by private firms and their production is governed by demand and supply movements.