The 2-m height attainable by Polytrichum moss is at the upper end of the size range reached by mosses. What accounts for the relative tallness of Polytrichum?

A) the cuticle that is found along the ridges of "leaves"
B) "leaves" that are more than one cell layer thick
C) high humidity of surrounding air which provides support against gravity
D) reduced size, mass, and persistence of the sporophytes which allows gametophores to grow taller
E) the presence of conducting tissues in the "stem"