The correct answer is option 'A' - Swidden agriculture is practiced in Asia, Africa, and South America. This traditional agricultural practice, also known as slash-and-burn agriculture or shifting cultivation, involves clearing land by cutting down and burning vegetation before planting crops. Here is a detailed explanation of the regions where swidden agriculture is practiced:

- Asia: Swidden agriculture is widespread in several countries in Asia. In Southeast Asia, countries like Thailand, Myanmar, Laos, and Cambodia have a long history of practicing this farming method. The indigenous communities in these countries have relied on swidden agriculture for generations, cultivating crops such as rice, maize, millet, and cassava. In addition to Southeast Asia, swidden agriculture is also practiced in parts of India, particularly in the northeastern states like Nagaland and Mizoram.

- Africa: Swidden agriculture is prevalent in various regions of Africa. In countries like Nigeria, Cameroon, Democratic Republic of Congo, and Central African Republic, indigenous communities have practiced this form of agriculture for centuries. The crops cultivated through swidden agriculture in Africa include yams, cassava, maize, and various vegetables. It is important to note that while swidden agriculture has been a sustainable farming method for many indigenous communities, it is facing challenges due to population growth, land scarcity, and deforestation.

- South America: Swidden agriculture is commonly practiced in parts of South America, particularly in the Amazon rainforest region. Indigenous communities in countries like Brazil, Peru, and Colombia have relied on this farming technique for centuries. They clear small patches of land in the forest, burn the vegetation, and plant crops such as cassava, bananas, beans, and sweet potatoes. However, swidden agriculture in the Amazon rainforest has faced criticism due to its contribution to deforestation and its impact on biodiversity.

In summary, swidden agriculture is practiced in Asia, Africa, and South America. It is a traditional farming method used by indigenous communities in these regions to grow crops for their sustenance. However, it is important to explore sustainable alternatives to swidden agriculture to address the environmental challenges associated with this practice.