Which maintenance task is crucial for preventing fuel-related issues in a mower?

Draining gasoline after each mowing season is vital for preventing fuel-related issues in a mower. Over time, fuel can degrade and form deposits that can clog the carburetor or fuel lines, leading to starting and performance problems. By removing gasoline at the season's end, you eliminate the risk of stale fuel causing issues when it's time to use the mower again. This practice helps ensure that fresh fuel is used, which is more reliable for engine performance.

While changing the spark plug, sharpening blades, and cleaning the undercarriage are important maintenance tasks that contribute to the overall efficiency and longevity of the mower, they do not specifically address fuel-related issues. Each of these tasks serves a different purpose—spark plugs impact ignition, sharp blades affect cutting performance, and a clean undercarriage helps with grass discharge and mower efficacy. However, they do not mitigate the risks associated with old or degraded fuel.