Please choose the correct ending to complete the given sentence: Cars & Other Vehicles: [header] How to make bio diesel [title] Work in a safe place. [step] This can mean in a clinical laboratory setting. You can find suitable laboratories at most colleges and research institutions.

Ending1: Working at home is also possible but requires caution-manufacturing your own biodiesel may be illegal and can put your house at risk of a fire, smoke or carbon monoxide. [substeps] A good work place will be well-ventilated and have clear access to running water, eye-wash stations, fire extinguishers, spill containment supplies, a fire alarm and a telephone to use in case of emergencies. Ending2: [title] Buy a pipe to fit your gas company. [step] A mid-powered piping all normal areas should be used. Ending3: Make sure you know the layout and detail of the environment, even if you are working in a private place. You are less likely to be caught if you're in an isolated place. Ending4: However, it can also mean in a rural area. [title] Find a spot with good heating (preferably with showers) at an angle from the area where you are experimenting.

Answer format: ending1/ending2/ending3/ending4