The correct option is Nageshwar and Balakot.
Explanation
The location of craft production centres in the Harappan Civilisation was often determined by the availability of raw materials. Settlements were strategically established near sources of materials such as shell, clay, or semi-precious stones to facilitate specialized manufacturing.
Analysis of the Sites:
- Nageshwar and Balakot: Both settlements are located near the coastline. Due to their proximity to the sea, they became specialized centres for making shell objects. The abundance of raw shells in these areas allowed artisans to produce items such as bangles, ladles, and inlay work, which were then transported to other Harappan settlements.
- Chanhudaro: While Chanhudaro was a significant craft centre exclusively devoted to production, it is primarily known for bead-making, shell-cutting, metal-working, seal-making, and weight-making, rather than being the primary source of shell objects compared to the coastal sites.
- Lothal: Lothal was a major centre for trade and bead-making (especially carnelian) but is not the primary answer for specialized shell object manufacturing in this specific context compared to the Nageshwar-Balakot pairing.
Key Takeaway: Nageshwar (Gujarat) and Balakot (Pakistan) were the two principal coastal sites in the Indus Valley Civilisation dedicated to the specialized production of shell objects.