Which sentence contains the correct use of a colon?

A. They saw buffalo and elk grazing in the meadow and drinking from the stream: around 630 p.m.

B. The Alaskan gold rush began in 1886: Fortymile Creek on the Yukon River was one famous site.

C. There were some things he forgot to bring along for his trip: a flashlight, gloves, and matches.

D. Life was tough in the winter: because there was daylight for only three hours a day.