Read the excerpt from “birches” by robert frost.

when i see birches bend to left and right
across the line of straighter darker trees,
i like to think some boy’s been swinging them.
but swinging doesn’t bend them down to stay.
ice-storms do that. often you must have seen them
loaded with ice a sunny winter morning
after a rain. they click upon themselves
as the breeze rises, and turn many-colored
as the stir cracks and crazes their enamel.
soon the sun’s warmth makes them shed crystal shells
shattering and avalanching on the snow-crust—
such heaps of broken glass to sweep away
you’d think the inner dome of heaven had fallen.

what is the best description of the theme of this excerpt?
a. the sun is more powerful than ice and snow.
b. birches are destroyed by both people and nature.
c. the sun has a wondrous effect on icy birch branches.
d. ice storms are nature’s most powerful force.