In the diagram shown you are being followed very closely by another vehicle, you should:

• A. Create more space in front of you by slowing down, until it is safe for the other vehicle to pass.
  Explanation:

  "Create more space so that you have a larger buffer to brake if you need to, and slow down so that the vehicle can pass you safely."
• B. Attempt to get the other vehicle to drop back by giving a hand signal.
• C. Brake hard to force the other vehicle to drop back.