Tanks have traditionally been an important source of irrigation in Andhra Pradesh, particularly in the:

The correct answer is: a) Rayalaseema region.

Tanks are small artificial reservoirs that are used to store rainwater. They have been traditionally used for irrigation in Andhra Pradesh, particularly in the Rayalaseema region. The Rayalaseema region is a semi-arid region that receives less rainfall than other parts of Andhra Pradesh. Tanks are an important source of water for irrigation in this region.

The other options are incorrect because:

• The Coastal plains are a fertile region that receives more rainfall than the Rayalaseema region. Tanks are not as important for irrigation in this region.
• The Eastern Ghats are a mountain range that runs through Andhra Pradesh. Tanks are not as common in this region because the terrain is not suitable for their construction.
• The Deccan Plateau is a large plateau that covers most of Andhra Pradesh. Tanks are found in all parts of the Deccan Plateau, but they are more important in the Rayalaseema region.