Introduction:
Shifting cultivation, also known as slash-and-burn agriculture, is a traditional farming practice in which parts of the forest are cut and burnt in rotation to clear land for cultivation. This method is commonly practiced in various parts of the world, including tropical rainforests. However, there are certain features that define shifting cultivation, and one of them is the absence of growing a single crop on the cleared plots.

Explanation:
Shifting cultivation involves a cyclical process where different stages are followed to ensure sustainable land use. Let's examine the features of shifting cultivation and understand why option 'D' is not a part of it.

1. Parts of the forest are cut and burnt in rotation:
In shifting cultivation, small areas of the forest are selectively cut down, and the vegetation is then burned. This process helps clear the land and provides nutrients through the ashes.

2. Seeds are sown in the ashes:
After the land is cleared and the ashes cool down, seeds are sown directly into the soil. The ashes act as a natural fertilizer, promoting the growth of crops.

3. Plots cleared are cultivated for a few years and then left fallow:
Once the crops are harvested, the cleared plots are cultivated for a limited period, usually a few years. During this time, farmers grow various crops, including staple food crops and cash crops. However, the land is not continuously cultivated for an extended period. Instead, it is left fallow or abandoned for a significant amount of time to allow natural regeneration of the forest.

Why option 'D' is not a feature of shifting cultivation?
Option 'D' states that a single crop is grown on these plots, which is not a characteristic of shifting cultivation. Shifting cultivation involves growing a variety of crops, not just a single crop. This practice promotes biodiversity and reduces the risk of crop failure due to pests or diseases. By growing multiple crops, farmers can also meet their dietary needs and have a diversified income source.

Conclusion:
Shifting cultivation is a sustainable agricultural practice that involves cutting and burning parts of the forest, sowing seeds in the ashes, and cultivating the cleared plots for a few years before leaving them fallow. It is important to understand the key features of shifting cultivation to appreciate its benefits and its role in maintaining ecological balance in forested areas.