Step 1: Set up the stack.
Five boxes P, Q, R, S, T sit one above another. Label positions 1 at the top down to 5 at the bottom.
Step 2: Fix the bottom.
T is at the bottom, so T takes position 5.
Step 3: Place P.
P is just above T, so P sits at position 4, directly over T.
Step 4: Order the Q-R-S block.
R is above S but below Q, giving the top-to-bottom order Q, then R, then S. These three fill the remaining positions 1, 2 and 3.
Step 5: Assemble the full stack.
From top to bottom: Q (1), R (2), S (3), P (4), T (5).
Step 6: Identify the top box.
Position 1 is Q, so Q is the box at the top, matching option 2.
\[ \boxed{Q} \]