Gabe is taller than Helen, Helen is shorter than Iris. Iris is shorter than both jack and Keiko. Which of the following statement is true?

A) The tallest person must be Gabe.
B) The tallest person must be Jack.
C) The tallest person must be Keiko.
D) Either Jack or Keiko must be the tallest person
E) Gabe, Jack, or Keiko could be the tallest person