Accepting an answer is not necessarily intended to mark [the] one that is correct, but rather the one that the asker found most helpful.
The official guidelines on accepting answers provide the following "golden rule":
The bottom line is to accept the answer that you found to be the most helpful to you, personally.
Obviously validity is a useful and important criterion for determining the "most helpful" answer. But it is certainly not the only one, especially not on a site such as this one, where the answers are likely to be less objective and clear-cut than those on (for example) Stack Overflow.
But it's really best not to worry too much about the accept rate. The guidelines for a healthy site don't mention acceptance rate at all, and for good reason. By far, the most important thing is voting. That is how we get the best answers (both the most technically accurate as well as the most useful) to the top, and it's how we regard those who provided such answers.
Voting is also important because it's the way the entire community can be involved in selecting the best answers. By contrast, accepting an answer is a privilege granted exclusively to the asker of the question.
So as another question here on Meta implores: Vote early, vote often