When viewing the Survey Statistics, there are clearly answers that are used as "correct" answers. However, there is no way to tel Canvas which of the survey answers should be viewed as correct. If the survey is converted temporarily to a graded quiz, it is possible to select the correct answer, save it, and convert back to a survey. At that point, viewing Survey Statistics clearly reflects the new choices of correct answers.
I understand that some may feel that surveys won't always have "correct" answers. But sometimes we need something like a Practice Quiz that nonetheless awards points for attempting it. Being able to select an OPTIONAL set of "Correct Answers" per survey question would allow for both true surveys and surveys that are doubling as exercises with correct answers that are only graded for completion.