Read this passage from Theodore Dreiser's Sister Carrie:

"It was truly a wintry evening, a few days later, when his one distinct mental decision was reached. Already, at four o'clock, the sombre hue of night was thickening the air. A heavy snow was falling—a fine picking, whipping snow, borne forward by a swift wind in long, thin lines."

Which detail establishes a relationship between setting and mood?

A.
"truly a wintry evening"

B.
"sombre hue of night"

C.
"swift wind in long, thin lines"

D.
"fine picking, whipping snow"