St1:
xyz --> negative.
We could have all x, y and z to the left of 0 on the number line and arranged such that z is not between x and y. We could also have all x, y and z to the left of 0 on the number line and arranged such that z is between x and y. Insufficient.
St2:
xy < 0 --> Either x or y is negative.
Same thing. I can arrange x, y or z to be between or to the left of x or y (whichever is negative). Insufficient.
Using St1 and St2:
xy < 0 and xyz < 0
Say x, is negative --> value of -5, y is positive, value of 5. The distance between x and y is 10. This satisfied the inequalitied xy < 0.
We know z must be positive, otherwise the inequality xyz < 0 cannot be satisfied, but we do not know which positive value z takes on the number line.
Ans E