Which missile system is being developed under Project Kusha to enhance India's air defence capabilities?

The correct option is Extended Range Air Defence System.

Explanation:
Project Kusha is an ambitious Indian defence project led by the Defence Research and Development Organisation (DRDO). Under this project, India is developing an indigenous Extended Range Air Defence System (ERADS).
This long-range surface-to-air missile system is designed to detect and destroy incoming enemy stealth fighters, aircraft, drone swarms, cruise missiles, and precision-guided munitions at ranges up to 350 km. It is often compared to or aimed at complementing systems like the Russian S-400 Triumf.