What are the recommendations for maintenance of a GLP system in a vehicle? The filter must be replaced regularly, for the first time 20,000 kilome...

What are the recommendations for maintenance of a GLP system in a vehicle?

The filter must be replaced regularly, for the first time 20,000 kilometers after the installation of the GLP system and at an interval of 30,000 kilometers thereafter.
It is recommended to replace spark plugs, check exhaust gases with an analyzer, check/replace the air filter, check/replace the gas filter, and check the proper functioning of the lambda probe every 20,000 kilometers.
It is recommended to check the valve clearance (valve play) every 30,000 kilometers.
It is important to maintain the gasoline level no lower than 1/4 of the tank capacity to avoid damaging the proper functioning of the gasoline pump.
In case of gas leaks, it is necessary to turn off the engine, turn off the dashboard lights, and switch to gasoline with the switch/indicator. Do not smoke and check that there is no ignition source near the vehicle. Once these checks have been made, it is possible to use the vehicle running on gasoline and it is suggested to go to an authorized installer/workshop.
a) Only the first and second statements are correct.
b) Only the second and fourth statements are correct.
c) Only the third and fifth statements are correct.
d) All statements are correct.