What is the extended metaphor utilized in the poem?

A. The narrator describes her climb up a dirty staircase which transforms into a crystal stair, which represents her ability to rise above difficulties.
B. The narrator describes a tiring climb up a beat-up staircase, which represents her persisting through difficulties and struggles in life.
C. The narrator compares a crystal staircase to her own life, symbolic of her own goals and the struggle towards them.
D. The narrator describes herself going down a decrepit staircase, a figurative depiction of her continued problems.