In a group of 6 persons of unequal heights, D is shorter than A and C, but taller than E and F. Two persons are taller than B, and one person is shorter than E. Which of the following inferences is NOT NECESSARILY valid?
1
A is the tallest of all.
2
C is taller than B.
3
F is the shortest of all.
4
B is taller than D.