With reference to India's satellite launch vehicles, consider the following statements : 1. PSLVs launch the satellites useful for Earth resources monitoring whereas GSLVs are designed mainly to launch communication satellites. 2. Satellites launched by PSLV appear to remain permanently fixed in the same position in the sky, as viewed from a particular location on Earth. 3. GSLV Mk III is a four-staged launch vehicle with the first and third stages using solid rocket motors; and the second and fourth stages using liquid rocket engines. Which of the statements given above is/are correct ?

The correct answer is A, 1 only. PSLV mainly carries Earth observation satellites to low orbits, GSLV was built for communication satellites, and the other two statements describe the rockets wrongly. The Polar Satellite Launch Vehicle places remote sensing satellites in sun-synchronous polar orbits a few hundred kilometres up, where they sweep over the whole Earth. The Geosynchronous Satellite Launch Vehicle, with its cryogenic upper stage, lifts heavier communication satellites towards the geostationary orbit about 36,000 km up. Only a geostationary satellite appears fixed in the sky; PSLV's low-orbit satellites cross the sky in minutes, so statement 2 is wrong. GSLV Mk III, now LVM3, has three stages, not four: two S200 solid strap-on boosters, the L110 liquid core stage and the C25 cryogenic upper stage, so statement 3 is wrong. The four-stage rocket with alternate solid and liquid stages is the PSLV itself. Option B is wrong because both its statements are false. Option C is wrong because statement 2 is false. Option D is wrong because statement 3 is false. Exam tip: PSLV has four stages (solid, liquid, solid, liquid); LVM3 has three.