With reference to India's satellite launch vehicles, consider the following statements:1.PSLVs launch the satellite 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 in 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?

1. A

   1 only

   (a) 1 only. PSLV is the workhorse for Earth-observation/remote-sensing satellites in polar/SSO orbits; GSLV (with cryogenic upper stage) is meant mainly for heavier communication satellites to GTO. Statement 1 is therefore correct. Statement 2 describes geostationary appearance, which PSLV payloads do not have. Statement 3 mis-counts GSLV Mk III: it is a three-stage vehicle (two solid strap-ons + liquid core + cryogenic upper), not four stages as described. Only 1 stands. This option is the official key.

2. B

   2 and 3

   (b) 2 and 3. Both remaining statements are false. This option is not the key.

3. C

   1 and 2

   (c) 1 and 2. Statement 1 is true; PSLV satellites are not fixed in the sky. This option is not the key.

4. D

   3 only

   (d) 3 only. The four-stage description of Mk III is wrong. This option is not the key.

Summary. Official key is (a) 1 only. PSLV launches Earth-resource satellites; GSLV is designed chiefly for communication satellites. A satellite that appears fixed in the sky is in geostationary orbit, typically a GSLV/GTO mission, not a PSLV polar bird. GSLV Mk III (LVM3) is three-stage, not the four-stage solid-liquid sandwich of statement 3. Hence only statement 1 is correct.