Prolonged liberal irrigation of agricultural fields is likely to create the problem of:

Prolonged liberal irrigation of agricultural fields is likely to create the problem of salinity. Salinity refers to the accumulation of salts in the soil, which can be harmful to plants. So, the correct answer is option D. Notice that the other options are not correct. Acidity refers to a decrease in the pH of the soil, which can be caused by factors such as acid rain or the use of certain fertilizers. Aridity refers to a lack of water in the soil, which is the opposite of what occurs with prolonged liberal irrigation. Metal toxicity refers to the accumulation of toxic metals in the soil, which can be caused by factors such as pollution or the use of certain fertilizers.