Who doesn’t live in flat-B of their floors?
I. T
II. P
III. R

Q lives in the west of O on an odd numbered floor.   V, who lives in the same type of flat as that of Q, lives either three floors below or above M in the same type of flat as that of M. It implies that Q, V, M live in flat-A of their floors while N, O live in flat-B of their floors. . R lives two floors above S such that they both live in either Flat-A or Flat-B of their floors. The next point is that V and M have two floors in between them and Q lives on an odd numbered floor. So, if we start placing Q, V, M, we can never place R and S who are two floors apart from each other in flat-A of their floors. So, it clearly means that R, S live in Flat-B. Thus, we finally get two cases: Case 1: V, M live on 5, 2 floors in any order. And U lives on 2nd floor. Now, if we see the first case R and V by placing N and O on odd numbered floors.U lives on 2nd floor , we will never be able to place U on 2nd floor.So, the first case gets rejected. We are left with Case 2 only. Case 2: Thus, U lives in flat-A on 2nd floor.