The correct answer is: a) Hilly areas under Jhum cultivation.
Jhum cultivation is a traditional form of shifting cultivation practiced in the hilly areas of Mizoram. It is a labor-intensive method of farming that involves clearing a patch of forest, burning the vegetation, and then planting rice in the ash-enriched soil. The land is then left fallow for several years to allow the forest to regenerate.
Jhum cultivation is a sustainable form of agriculture that has been practiced in Mizoram for centuries. However, it is under threat from deforestation, population growth, and the development of commercial agriculture.
Option b) River valleys with irrigation is incorrect because rice cultivation in Mizoram is not primarily practiced in river valleys. The state has a very low population density and most of the land is not suitable for irrigation.
Option c) Coastal plains is incorrect because Mizoram is a landlocked state and does not have any coastal plains.
Option d) Terraced fields is incorrect because rice cultivation in Mizoram is not primarily practiced in terraced fields. Terraced fields are used for rice cultivation in some parts of the state, but they are not as common as jhum cultivation.