Final answer:
The elimination of unexploited profit opportunities in a market does not require all participants to be well informed, but rather just some. These well-informed participants help ensure that prices reflect all available information by acting on profit opportunities quickly.
Step-by-step explanation:
The elimination of unexploited profit opportunities requires that some market participants be well informed. This concept is rooted in the Efficient Market Hypothesis (EMH), which suggests that stocks always incorporate and reflect all relevant information. As a result, no trader can consistently achieve higher-than-average returns. However, for a market to be efficient, not all participants need to be well informed about every aspect of the market. It is enough if some participants are well-informed; these individuals or entities will quickly act on any unexploited profit opportunities, thus driving prices to reflect all available information.