Punjab has the highest percentage of net irrigated area among Indian states, primarily due to:

High rainfall
Extensive canal network
Abundant groundwater
Large number of lakes

The correct answer is: b) Extensive canal network.

Punjab has the highest percentage of net irrigated area among Indian states, primarily due to its extensive canal network. The canal network was built by the British in the 19th century to irrigate the fertile plains of Punjab. The canals are fed by the Sutlej and Beas rivers, which flow from the Himalayas. The canal network is a vital part of the Punjab economy, as it allows farmers to grow a variety of crops, including wheat, rice, and sugarcane.

The other options are incorrect. Option a) is incorrect because Punjab does not have high rainfall. Option c) is incorrect because Punjab does not have abundant groundwater. Option d) is incorrect because Punjab does not have a large number of lakes.