Identification of the place where the mature Harappa culture degenerated and transformed itself:

The correct answer is option 'A' - Rangpur. Rangpur is a significant archaeological site located not far from Lothal, which was one of the major cities of the ancient Indus Valley Civilization. It is believed that Rangpur was a key center of the Harappan culture, where the mature Harappa culture eventually degenerated and transformed into other cultures.

Explanation:

1. Rangpur as a significant archaeological site:
- Rangpur is an archaeological site situated in the state of Gujarat, India. It is located in the district of Ahmedabad, not far from Lothal, another prominent site of the Indus Valley Civilization.
- Excavations at Rangpur have revealed the presence of a well-planned ancient settlement, which suggests that it was an important center during the Harappan period.

2. Degeneration and transformation of the Harappa culture:
- The Harappa culture, also known as the Indus Valley Civilization, was a highly advanced urban civilization that flourished in the Indian subcontinent from approximately 2600 BCE to 1900 BCE.
- However, towards the later stages of the Harappan civilization, there was a decline and degeneration of the once prosperous cities. Several factors, including environmental changes, economic decline, and possibly invasions or migrations, have been suggested as reasons for the decline.
- Rangpur is believed to be one of the sites where this degeneration and transformation of the Harappa culture occurred. The evidence found at Rangpur indicates a shift in the cultural practices and material remains, suggesting a transition from the mature Harappan culture to subsequent cultures.

3. Transformation into other cultures:
- After the decline of the Harappan civilization, the region underwent significant cultural and social changes. The transformation of the mature Harappa culture at Rangpur resulted in the emergence of subsequent cultures.
- The subsequent cultures that evolved after the Harappan period in the region include the Painted Grey Ware culture, associated with the arrival of the Indo-Aryans, and the early historical period marked by the rise of cities like Rajgir and Pataliputra.

In conclusion, Rangpur is the place not far from Lothal where the mature Harappa culture degenerated and transformed itself into subsequent cultures. The archaeological excavations at Rangpur have provided valuable insights into the decline and transformation of the Harappan civilization, shedding light on the cultural dynamics of the region during that period.