The correct option is Tapping the gold mines of Karnataka..
Explanation
The Mauryan Empire was a vast centralized state divided into provinces for administrative efficiency. According to Ashokan inscriptions, there were five major political centres: the imperial capital at Pataliputra and four provincial capitals-Taxila (North), Ujjayini (West), Tosali (East), and Suvarnagiri (South).
Detailed Analysis:
- Suvarnagiri (Option a): The name Suvarnagiri literally translates to "the golden mountain." It was the southernmost provincial capital of the Mauryan Empire, located in present-day Karnataka. This location was strategically significant for controlling the southern territories and, most importantly, for tapping into the gold mines of Karnataka (such as the Hatti gold mines).
- Taxila (Option c): Located in the northwest, Taxila was a gateway to Central Asia and was crucial for managing trade routes, including the Silk Route connections.
- Tosali (Option d): Located in Kalinga (modern-day Odisha), Tosali was important for coastal defense and trade in the east.
- Pataliputra (Option b): The imperial capital controlled the riverine trade along the Ganga and served as the central administrative hub.
Key Takeaway:
The Mauryan administration utilized specific provincial centres for strategic economic and military goals: Taxila for trade, Ujjayini for commercial routes, Tosali for coastal control, and Suvarnagiri specifically for accessing the mineral resources (gold) of the Deccan.