Shale gas is a natural gas that is found trapped within shale formations. - In India, shale gas resources are found in several regions. - The Cambay Basin, located in western India, is one of the oldest and most productive sedimentary basins in India and has been a major source of conventional oil and gas. - The Cauvery Basin and Krishna-Godavari Basin are also known to have shale gas resources. Therefore, all three basins mentioned in the options are known to have shale gas resources. Hence, the correct answer is (d) 1, 2 and 3.