Answer : 4. "तेजस"
Explanation :

The HAL Tejas is a lightweight multirole fighter developed by India. It is a tailless, compound delta wing design powered by a single engine. It came from the Light Combat Aircraft (LCA) Programme, which began in the 1980s to replace India’s against MiG-21 fighters. Later the LCA was officially named ‘Tejas’, meaning ‘Radiance’ by then Prime Minister Atal Bihari Vajpayee.