How countlessly they congregate

O'er our tumultuous snow,
Which flows in shapes as tall as trees
When wintry winds do blow!--

As if with keenness for our fate,
Our faltering few steps on
To white rest, and a place of rest
Invisible at dawn,--

And yet with neither love nor hate,
Those stars like some snow-white
Minerva's snow-white marble eyes
Without the gift of sight.

'They' in the first line refers to what?
A. stars
B. snowflakes
C. trees
D. people

Is it A?

Yes,

This is the poem, "Stars" by Robert Frost.

Yes, the answer is A. The pronoun "they" in the first line refers to the stars. This can be inferred from the following lines that describe the stars congregating over the snowy landscape. To arrive at this answer, you should analyze the given lines of the poem and identify the context clues that suggest the correct interpretation.