The phrase "color of the spirit" means______.

A．We stand to gain most from the reading of political treatises.
B．The first step on the moon' was mankind' s most important moment.
C．The function of poetry is to elevate the relationship between the practical arts and everyday life.
D．Great literature must address itself to fundamental philosophical truths rather than to material progress.

A．literature of knowledge
B．expressive of the grandeur of truth
C．a kind of philosophical cookbook
D．infinitely complex in structure