This must be true. If most people who invest don’t do any research, and most people who invest also profit, there must be some people who belong to both groups. In other words, there must be overlap, as both groups encompass more than half of all people who invest.

This could be false. Most people who invest don’t do their own research; of this majority, some rely on their broker and others on hunches. There could be a third sub-group that relies on something other than a broker or hunches. We can’t assume these are the only sub-groups.

This could be false. We don’t know how large the group of people who do some research while also relying on brokers or hunches is, but we do know they belong to the minority of people who do their own research. They could also be in the minority who don’t profit.

This could be false. We know some people who invest without doing research make a profit—we have no reason to believe most of them do.

This could be false. We know most people who invest don’t do their own research: within this group, some people make a profit and some rely solely on their broker. We don’t know if these groups overlap and how many people (if any) who rely solely on their broker make a profit.