What may be used in addition to the red reflector on a bicycle for nighttime riding?

• A red light on the rear visible from a distance of 500 feet.
  Explanation:

  "A red light on the rear, visible from a distance of 500 feet, may be used in addition to the red reflector on a bicycle for nighttime riding."
• An amber light on the rear visible from a distance of 500 feet.
• A blue light on the front visible from a distance of 500 feet.
• A green light on the front visible from a distance of 500 feet.