Read the following sentence from John Gardner's Grendel:

"I played my way farther out into the world, vast cavern aboveground, cautiously darting from tree to tree challenging the terrible forces of night on tiptoe (16)."

Which statement best describes the impact the underlined phrase has on the meaning of this sentence?

A. It shows that Grendel didn't want to challenge the terrible forces at all.
B. It demonstrates that Grendel knew he needed to rise above the forces of night.
C. It implies that the challenge was not fearless, but timid.
D. It indicates that the forces of night must be challenged.