Please choose the correct ending to complete the given sentence: Work World: [header] How to better understand fracking [title] Drill a well. [step] A well is drilled vertically into the ground until it reaches the permeable shale layers. [substeps] Once the digging has hit the gas rich layers, redirect it horizontally into the rock layers.

Ending1: Take your 12-inch needle and a spade and drill through the rock layers, one layer at a time, until you reach the desired depth. You can drill the hole inside the rock in any direction using a rhythmic pattern. Ending2: The digging is now parallel to the ground above, but at an immense depth below the surface (anywhere around 7 , 000 to 12 , 000 feet). The well is surrounded by a protective steel casing, and it is surrounded by both steel and concrete when it is drilled past the underground aquifer level. Ending3: This pattern is: top of rocks top of top rock rock top bottom sand bottom top filter [title] Drill the mouth. [step] The mouth of the well is facing downwards, which is the main feature of the hole, and becomes the fuel for your fracking machine. Ending4: Put the shovels in a straight line just before you dig and slowly dig back. This will minimize the amount of time it takes to dig back in.

Answer format: ending1/ending2/ending3/ending4