Seven executives P, Q, R, S, T, U andW reach office in a particular sequence.
U reaches immediately before P but does not immediately follow S. R is the last one to reach office. T follows immediately after P and is subsequently followed by W. Among the executives, who reaches the office first ? 

Answer: B. S

Clearly, U is followed by P;  P by T;  T by W.
Now, U does not immediately follow S and R reaches last.
So, the order of reaching office is : S, Q, U, P, T, W, R.

S is the first to reach office.