Explanation:

All statements are correct.

• India’s first solar mission, Aditya-L1, has recently reached the spaceport in Sriharikota.

• Aditya L1 is the first space-based Indian mission to study the Sun.

• It will be launched by the PSLV-XL launch vehicle.

• The spacecraft shall be placed in a halo orbit around the Lagrange point 1 (L1) of the Sun-Earth system, which is about 1.5 million km from the Earth.

• A satellite placed in the halo orbit around the L1 point has the major advantage of continuously viewing the Sun without any occultation/eclipses.

• This will provide a greater advantage in observing solar activities and their effect on space weather in real-time.

• Lagrangian points, also known as Lagrange points or libration points, are specific locations in space where the gravitational forces of two large bodies, such as a planet and its moon or a planet and the Sun, produce enhanced regions of gravitational equilibrium.

• In these points, the gravitational pull from the two bodies creates a stable or quasi-stable region where a third, smaller object can maintain a relatively constant position relative to the larger bodies.

• There are five primary Lagrangian points, labeled L1 through L5, in a Sun-Earth system.

Hence option 4th is correct.