Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to heat and apply solder [title] Cut, file, sand or otherwise flatten the joining surfaces as much as possible. [step] However don't overly polish the surfaces as a slightly rough or' keyed' surface usually leads to a stronger bond. It is crucially important in any soldering task to ensure that the pieces to be joined match up closely with the smallest gap possible.

Ending1: [substeps] The inch gap will count for an ounce of your solder. Although this extra space allows the solder to adhere evenly, it still won't provide the uniform coverage you want. Ending2: [title] Use your fine-grit sandpaper to sand down the sides of your bond with precise, even strokes. [title] Remove your newly joined links from their bond. Ending3: [substeps] Cut, file, sand or otherwise flatten the separating surfaces as much as possible to ensure that the pieces to be joined together meet when finished. Skip this section if you wish to create fence rails. Ending4: [title] Wash the pieces clean and if possible' pickle' them. [step] Pickling means immersing the pieces or covering the joint area in an acid cleaning fluid.

Answer format: ending1/ending2/ending3/ending4