Apart from staple grains such as wheat and barley, which of the following crops was extensively cultivated by the inhabitants of the Harappan Civilization?

The correct option is Cotton.

The inhabitants of the Harappan Civilization (also known as the Indus Valley Civilization) were among the first people in the world to grow and utilize cotton. Archaeological evidence, such as preserved fragments of woven cotton cloth found at Mohenjo-daro and cotton seeds found at Mehrgarh, confirms its extensive cultivation.

While staple grains like wheat and barley formed the agricultural foundation for food, cotton was widely cultivated to produce textiles, which were vital for domestic clothing and trade.

Other options such as Maize originated in the Americas and were introduced to the Indian subcontinent much later, while Sugarcane was not a primary cultivated crop during the Harappan era.