The 2-M Height Attainable by Polytrichum Moss Is at the Upper

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 provides support against gravity
D) reduced size, mass, and persistence of the sporophytes allows gametophores to grow taller
E) the presence of conducting tissues in "stem"