Please choose the correct ending to complete the given sentence: Home and Garden: [header] How to kosher an oven [title] Use a caustic oven cleaner. [step] Begin the koshering process by spraying a caustic oven cleaner inside of your oven. Leave the oven on for as long as the instructions recommend after you've finished spraying the oven with the cleaner.

Ending1: There will be some residue left over from the cleaner as it sets into the pan, but it will lift away quickly and easily. Wipe the inside down to remove any residual material. Ending2: [substeps] Do not use caustic cleaners on ovens that may not remain fully operating after the first 10 minutes. As the oven will still be open during this time, it's a good idea to conduct the cleaning and polishing process at this time. Ending3: As the oven will soon be full of the cleaner, you want to leave it on for a total of 3 hours. [substeps] For 4 hours, choose a silicone-based oven cleaner. Ending4: The cleaner will loosen up the hardened grease. Scrape the oven with steel wool once the oven has cooled down.

Answer format: ending1/ending2/ending3/ending4