Choose the sentence that correctly uses a colon.

A. I am telling you that: she has got to go!

B. Last time I went bungee jumping: I did a swan dive from the platform.

C. Before going sky-diving, be sure to bring the following: goggles, a parachute, and ample courage.

D. Racing mountains bikes requires excellent physical fitness: but racing also requires a certain amount of recklessness.