From where was the 100th Space Mission of ISRO launched in September 2012?

The answer is A) Sriharikota. ISRO's orbital launches go up from the Satish Dhawan Space Centre (SDSC SHAR) on Sriharikota island in Andhra Pradesh, which is ISRO's main launch complex. The September 2012 PSLV-C21 mission, which carried SPOT-6 and PROBA-V, was launched from there on 9 September 2012. Whatever the exact count used for the 'hundredth' mission, the launch site is Sriharikota.

• B) Mahendragiri is the ISRO propulsion complex in Tamil Nadu, where engines are tested. It does not launch rockets.
• C) Thumba is the Thumba Equatorial Rocket Launching Station near Thiruvananthapuram. It was ISRO's early sounding-rocket site and has no role in orbital missions.
• D) Bengaluru is the home of ISRO headquarters and the U R Rao Satellite Centre, which build and control satellites. Launches do not take place there.

The core concept is ISRO's facility mapping: assembly, testing, control and launch are spread across different centres. This is useful for Science and Technology and for Mains answers on India's space programme and the strategic value of Sriharikota's east-coast location.

Trap: candidates pick Thumba because it is the older, well-known launch site. Thumba was used for sounding rockets, not orbital missions.