The Krishna and Godavari deltas have extensive networks of:

Irrigation canals
Tube wells
Sprinkler systems
Drip irrigation systems

The correct answer is: a) Irrigation canals.

Irrigation canals are artificial channels that are used to transport water from a source, such as a river or lake, to a field or other area where it is needed for irrigation. Irrigation canals are a major source of water for agriculture in many parts of the world, including the Krishna and Godavari deltas in India.

Tube wells are vertical holes that are drilled into the ground to extract groundwater. Tube wells are a common source of water for irrigation in many parts of the world, but they are not as common in the Krishna and Godavari deltas as irrigation canals.

Sprinkler systems are systems that use sprinklers to spray water onto crops. Sprinkler systems are a common type of irrigation system in many parts of the world, but they are not as common in the Krishna and Godavari deltas as irrigation canals.

Drip irrigation systems are systems that deliver water directly to the roots of plants through a network of small pipes. Drip irrigation systems are a more efficient type of irrigation system than other types of irrigation systems, and they are becoming more common in the Krishna and Godavari deltas.

Irrigation canals are the most common type of irrigation system in the Krishna and Godavari deltas. They are used to irrigate a wide variety of crops, including rice, cotton, and sugarcane. Irrigation canals are a vital part of the agricultural economy in the Krishna and Godavari deltas.