In "birches" the author uses the phrase "shed crystal shells" to describe

A. a collection of glass figurines
B. the ice cracking off of the trees
C the melting of snow on the rocks
D. the shine of seashells glistening on the beach

B. the ice cracking off of the trees

B. the ice cracking off of the trees

To determine the answer to this question, we should analyze the poem "Birches" by Robert Frost and look for any hints or descriptions that relate to the phrase "shed crystal shells." By understanding the context and imagery used in the poem, we can deduce the correct answer.

The phrase "shed crystal shells" appears in the following lines of the poem:

"Once they are bowed
So low for long, they never right themselves:
You may see their trunks arching in the woods
Years afterwards, trailing their leaves on the ground
Like girls on hands and knees that throw their hair
Before them over their heads to dry in the sun.
But I was going to say when Truth broke in
With all her matter-of-fact about the ice-storm
I should prefer to have some boy bend them
As he went out and in to fetch the cows--
Some boy too far from town to learn baseball,
Whose only play was what he found himself,
Summer or winter, and could play alone.
One by one he subdued his father's trees
By riding them down over and over again
Until he took the stiffness out of them,
And not one but hung limp, not one was left
For him to conquer. He learned all there was
To learn about not launching out too soon
And so not carrying the tree away
Clear to the ground. He always kept his poise
To the top branches, climbing carefully
With the same pains you use to fill a cup
Up to the brim, and even above the brim.
Then he flung outward, feet first, with a swish,
Kicking his way down through the air to the ground.
So was I once myself a swinger of birches.
And so I dream of going back to be.
It's when I'm weary of considerations,
And life is too much like a pathless wood
Where your face burns and tickles with the cobwebs
Broken across it, and one eye is weeping
From a twig's having lashed across it open.
I'd like to get away from earth awhile
And then come back to it and begin over.
May no fate willfully misunderstand me
And half grant what I wish and snatch me away
Not to return. Earth's the right place for love:
I don't know where it's likely to go better.
I'd like to go by climbing a birch tree,
And climb black branches up a snow-white trunk
Toward heaven, till the tree could bear no more,
But dipped its top and set me down again.
That would be good both going and coming back.
One could do worse than be a swinger of birches."

From these lines, we can infer that the ice-storm and the subsequent actions of the speaker and a boy are described here. The winter imagery associated with the ice-storm suggests that the phrase "shed crystal shells" refers to the ice cracking off the trees, similar to how shells might fall off the surface of an object. This supports that the correct answer is B. the ice cracking off of the trees.