Ferns Occupy Diverse Habitats and Have Unique Adaptations

Ferns occupy diverse habitats and have unique adaptations. Which of the following statements regarding fern adaptations is NOT true?

A) Tiny aquatic ferns, such as Salvinia, float on the surface of the water.
B) Tree ferns hold their stems upright by forming a rigid matrix of roots that grows down from the leaves.
C) Azolla is a tiny aquatic fern that has been used for centuries as a biofertilizer of rice.
D) Unlike many other groups of plants, ferns have not been found to have symbiotic associations with nitrogen-fixing bacteria.
E) Approximately 40% of living ferns are epiphytes.