Answer :
Final answer:
In an internal combustion engine, it's the spark plugs that need to be changed regularly in order to create the necessary ignition. They initiate an electrical spark that sets off the air-fuel mixture within the engine, and hence need to be replaced periodically for optimal performance.
Explanation:
In an internal combustion engine, like the one found in a tractor, it is the spark plugs that require regular changing in order to create the necessary ignition. Spark plugs generate an electrical spark that ignites the air-fuel mixture inside the engine's cylinders. Over time, spark plugs can become covered in carbon deposits, reducing their effectiveness. As a result, they need to be changed periodically to maintain the performance of the engine. Other components like piston bearings, oil pans, and compressor valves, while crucial to engine operation, do not directly influence engine ignition and don't require as frequent maintenance.
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