What is the central metaphor utilized in the poem?

Well, son, I tell you Life for me ain't been no crystal stair.
Its had tacks in it,
And splinters,
And boards torn up.
And places with no carpet on the floor-
Bare
But all the time I'se been a-climbin' on,
And reachin' landin's,
And turnin' corners,
And sometimes gain in the dark
Where there ain't been no light
So boy, don't you turn back
Don't you set down on the steps
Cause you finds it's kinder hard.
Don't you fall now-
Far I'se still gold, honey,
I'se still climbin And life for me ain't been no crystal stair

A .The narrator describes a tiring climb up a beat-up staircase, which represents her persisting through difficulties and struggles in life

B. The narrator compares a crystal staircase to her own life, symbolic of her own goals and the struggle towards them.

C. The narrator describes her climb up a dirty staircase which transforms into a crystal stair, which represents her ablity to rise above difficulties

D. The narrator describes herself going down a decrepit staircase, a figurative depiction of her continued problems.​