The question asks for ISRO's first mission built to study X-ray, optical and UV sources at the same time. Look at what each option actually is.
Only Astrosat is an ISRO observatory built to observe X-ray, optical and UV sources together, while the other three fail on either the "ISRO" part or the "multi-band astronomy" part.
The correct answer is Astrosat.
The question asks where APPLE, ISRO's first communication satellite, was launched from. Look at what each site was actually used for around 1981.
Only Kourou was actually capable of launching a satellite in 1981, so APPLE went up from there aboard an Ariane rocket.
The correct answer is Kourou, French Guiana.
The question asks for the spacecraft that was successfully sent to probe the planets of the solar system. Look at what actually happened to each named craft.
Three of the four never even escaped Earth orbit or never flew at all, while Mariner 10 actually completed its planetary flybys.
The correct answer is Mariner 10.
The question asks for the code name of India's first nuclear test, conducted in 1974. Check what each option actually refers to.
Two of the four names are missiles and one is the wrong nuclear test, leaving only the correct 1974 test.
The correct answer is Smiling Buddha.
The question asks how far NaviC's coverage extends beyond India. Check each figure against ISRO's stated design.
Only one of the four figures matches the officially stated coverage extension.
The correct answer is 1,500 km.