<p>I agree with everyone else. These are probably different sections of the same course. You pick just one of the sections to enroll in. You’d MW 12-12:50, OR M 2:30-3:20, OR M 3:30-5:20. Not all three. </p>
<p>It’s also possible that these are individual lecture, lab, and discussion sections. If that’s the case, then I’d assume that MW 12-12:50 is the lecture portion, M 2:30-3:20 is the discussion section, and M 3:30-5:20 is the lab portion. </p>