What is the role of the Choke and when do we use it?

• It adjusts the mixture of oxygen and carbon dioxide to start a hot engine
• It adjusts the mixture of oxygen and gasoline to start a hot engine
• It adjusts the mixture of air and gasoline supplied to the engine to start a cold engine
  Explanation:

  "It is used to help start the motorcycle by adjusting the mixture of gasoline and air supplied to the engine. It is used when starting a cold engine"
• None of the above