The correct answer is A. liming.
Liming is the process of adding calcium or magnesium carbonate to soil to neutralize acidity. It is the most common way to correct soil acidity, and it is effective in a wide range of soils.
Proper irrigation is important for maintaining soil pH, but it does not directly correct acidity. Irrigation can help to leach out acids from the soil, but it can also add water that can dissolve more acids from the soil.
Application of fertilizers can also affect soil pH, but the effect depends on the type of fertilizer. Some fertilizers, such as ammonium sulfate, can make soil more acidic, while others, such as lime, can make soil more alkaline.
Adding sodium hydroxide is not a recommended way to correct soil acidity. Sodium hydroxide is a strong base, and it can damage soil structure and make it difficult for plants to grow.
In addition to liming, there are other ways to correct soil acidity. These include adding organic matter, such as compost or manure, to the soil, and growing plants that tolerate acidic soils.