The Tirap Frontier Tract was a region where some tribes practiced a loose form of:

Zamindari system
Feudalism
Headhunting
Shifting cultivation

The correct answer is: d) Shifting cultivation.

Shifting cultivation, also known as swidden agriculture or slash-and-burn agriculture, is a traditional agricultural system in which the natural vegetation is cleared and the soil is cultivated for a short period of time. After a few years, the land is abandoned and allowed to regenerate, while the farmers move on to clear a new area.

Shifting cultivation is a sustainable form of agriculture that has been practiced for centuries by many different cultures around the world. However, it is often misunderstood and criticized by outsiders. Some people believe that shifting cultivation is a destructive practice that leads to deforestation and soil erosion. However, this is not always the case. When practiced correctly, shifting cultivation can be a sustainable way to manage land and produce food.

The Tirap Frontier Tract was a region in northeastern India where some tribes practiced a loose form of shifting cultivation. The tribes would clear a small area of forest, burn the vegetation, and then plant crops in the ash-enriched soil. After a few years, they would abandon the area and move on to clear a new one. This practice allowed the tribes to live in harmony with the environment and avoid over-exploiting the land.

The other options are incorrect because they do not describe the practice of shifting cultivation. Zamindari system is a type of land tenure system in which the land is owned by a landlord and leased to tenants. Feudalism is a social system in which land is owned by a small number of powerful lords and worked by peasants. Headhunting is a practice in which people are killed and their heads are taken as trophies.