Read the poem "Stopping by Woods on a Snowy Evening" by Robert Frost.

Whose woods these are I think I know.
His house is in the village, though;
He will not see me stopping here
To watch his woods fill up with snow.

My little horse must think it's queer
To stop without a farmhouse near
Between the woods and frozen lake
The darkest evening of the year.

He gives his harness bells a shake
To ask if there's some mistake.
The only other sound's the sweep
Of easy wind and downy flake.

The woods are lovely, dark, and deep,
But I have promises to keep,
And miles to go before I sleep,
And miles to go before I sleep.

Which is the best explanation of what the phrase “miles to go before I sleep” symbolizes in Frost’s poem?

A.
age; The speaker is aware of running out of time at the end of his life.
B.
future; The speaker has a need to keep moving and experiencing life.
C.
hardship; The speaker has too many problems to overcome in life.
D.
regrets; The speaker is sorry for mistakes he has made in life.