The correct option is 1 only because the PSLVs (Polar Satellite Launch Vehicles) are indeed designed primarily for launching satellites for Earth observation and resource monitoring, while the GSLVs (Geosynchronous Satellite Launch Vehicles) are tailored for communication satellites that require geostationary orbits. Statement 2 is incorrect; satellites in geostationary orbit (like many GSLV-launched satellites) appear fixed relative to a point on Earth, not those in the polar orbits of PSLV-launched satellites, which move relative to the Earth's surface. Statement 3 is also incorrect; GSLV Mk III, also known as LVM-3, typically employs a mix of solid and liquid stages, but the configuration described does not accurately reflect its actual design. Thus, only the first statement aligns with the standard knowledge expectations of UPSC-level sources.