The correct answer is (a) GSAT-6.
GSAT-6 is a geostationary communication satellite launched by India on 29 September 2012. It was the first satellite to be launched by India’s Geosynchronous Satellite Launch Vehicle (GSLV) Mk-II. The satellite was designed and developed by the Indian Space Research Organisation (ISRO).
GSAT-6 has a mass of 2,250 kg and is equipped with 12 C-band and 12 Ku-band transponders. It is designed to provide communication services to India and neighboring countries.
The satellite was launched from the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh. It was placed into a geostationary orbit at an altitude of 36,000 km.
GSAT-6 is a major milestone in India’s space program. It is the first satellite to be launched by India’s GSLV Mk-II and the first satellite to be equipped with 12 C-band and 12 Ku-band transponders. The satellite is expected to provide communication services to India and neighboring countries for many years to come.
The other options are incorrect because they are not satellites that were launched by India on 29th September, 2012.