Jhum cultivation, or shifting cultivation, is practiced in:

River valleys
Hilly areas
Flood plains
Plains region

The correct answer is: b) Hilly areas.

Jhum cultivation, also known as shifting cultivation, is a traditional agricultural practice that involves clearing a piece of land by cutting and burning the vegetation, then planting crops on the land for a few years before abandoning it and moving on to a new plot. This type of cultivation is often practiced in hilly areas, where the land is not suitable for permanent agriculture.

There are several reasons why jhum cultivation is practiced in hilly areas. First, the steep slopes of hills make it difficult to use machinery for cultivation, so jhum cultivation is often the only option available. Second, the thin soils of hills are quickly depleted by continuous cultivation, so jhum cultivation allows the land to recover its fertility before it is used again. Third, the forests that are cleared for jhum cultivation provide a source of firewood and building materials.

However, jhum cultivation also has a number of negative environmental impacts. The clearing of forests for jhum cultivation contributes to deforestation and soil erosion. The burning of vegetation releases greenhouse gases into the atmosphere, and the use of slash-and-burn methods can lead to the loss of biodiversity.

In recent years, there has been a growing effort to promote sustainable alternatives to jhum cultivation. These alternatives include terracing, which helps to prevent soil erosion, and the use of improved seeds and fertilizers, which can help to increase crop yields.

In conclusion, jhum cultivation is a traditional agricultural practice that is often practiced in hilly areas. It has a number of negative environmental impacts, but there are also a number of sustainable alternatives that are being promoted.