by noah Mon Sep 26, 2011 6:40 pm
If we know that two sessions are attended on day 3, we know that it's M and S (since T is restricted to days 1 and 2). So, we have M attending H or R and S attending whichever one M doesn't.
(C) is true because it's impossible for them to attend the same session on day 3, or else we wouldn't have 2 sessions attended. And, it's impossible for them to attend another session together since the only sessions they can go to are H and R, so throughout the game we know they will each do an H and each do an R.
Since day 3 has them already doing opposite topic sessions (to "cover" two sessions), it's impossible that on an earlier day they both did the same one because either S or M would have to be repeating the session on day 3, which is prohibited.
(A) could be true - S and M could do H and R respectively on day 1, and the opposite on day 3 - but it could also be false if either M or S instead attends a session on day 2, or both of them do.
(B) is similar to (A), just switch the days!
(D) could be false - M and T can attend a session together on day 1 or 2.
(E) could be false. There's no rule that every session needs to be attended. So, T could stick with H and R sessions, just like M and S are doing.