Write the next sentence in the following story.

How to replace your mercury optimax dfi air injectors
Read your engine owners manual.
Purchase and read a factory shop manual.
Review all safety precautions.

Available choices:
1). Remove the mercury flywheel from the fuel tank. Inspect the exposed area of the engine for smoke coming out or sparks..
2). Make sure your fuel and heater are turned off. Keep the batteries charged on all cylinders to prevent theft and injury..
3). Touching the air injectors after they are clean will pose a serious health risk. Press and hold the igniter tab of the gasoline tank..
4). Review tips on various websites such as airinjectors. Com Consult with your local mercury dealer or certified merc tech... The answer should be
4).