Wearing a helmet visor or goggles when riding will:

• A. Not make much difference to your riding on a fine day when there is no wind.
• B. Protect your eyes from the wind, dust, rain, insects or stones thrown up by other vehicles.
  Explanation:

  "Your eyesight can be seriously damaged if you are hit in the eye by an object when riding at speed, therefore you should always wear a helmet visor or goggles."
• C. Reduce your vision and should only be worn in the rain.