Pg 521 (453) - Q20
If the tallest person is denoted by T, the 2 shortest students are
denoted by S1 and S2, and the 2 remaining medium students are denoted by
M1 and M2, then the possible arrangements are:
T must stay in the middle, and S1 and S2 must be on the end.
S1 M1 T M2 S2
S1 M2 T M1 S2
S2 M1 T M2 S1
S2 M2 T M1 S1
There are 4 possible arrangements, so the answer is B.