The correct answer is: a) Drought-prone areas.
Protective irrigation is the practice of irrigating crops during periods of drought or water stress. It is particularly important in drought-prone areas, where crops are at risk of dying if they do not receive enough water. Protective irrigation can help to ensure that crops continue to grow and produce even during periods of drought.
In areas with high-value crops, protective irrigation can also be important, as it can help to protect the investment that has been made in these crops. However, it is not as essential in these areas as it is in drought-prone areas, as crops in these areas are less likely to die if they do not receive enough water.
In areas with saline soils, protective irrigation can actually be harmful, as it can lead to the accumulation of salt in the soil. This can make it difficult for crops to grow.
In areas with poor drainage, protective irrigation can also be harmful, as it can lead to waterlogging of the soil. This can also make it difficult for crops to grow.
Therefore, the correct answer is: a) Drought-prone areas.