Final answer:
The El Niño phenomenon, caused by the weakening of trade winds, is most likely responsible for flooding in California due to periods of heavy rains. It impacts the selection and yield of crops, aircraft visibility, and flight timing.
Step-by-step explanation:
The weather phenomenon most likely to cause periodic occurrences of higher than average precipitation in California, leading to flooding due to heavy rainfall, is El Niño. This occurs due to the weakening of trade winds, which allows warmer water to move towards the east along the equator, which in turn influences global weather patterns and can result in extreme weather, including heavy rains in areas like California.
As for how these climatic conditions can impact various sectors, they all can indeed be affected. A. The selection of crops is impacted as different crops require specific climate conditions. B. Seasonal crop yield is affected by weather, with changes in rainfall and temperature potentially boosting or reducing yields. C. Aircraft visibility can be compromised during severe weather events like heavy rainfall or fog, which are influenced by climate conditions. D. Flight timing may also be affected by weather-related delays or the necessity to reroute flights due to climatic disruptions.