Correct Option
The tail of a comet is directed away from the Sun primarily due to two forces: solar radiation pressure and solar wind. As a comet approaches the Sun, its icy nucleus heats up, releasing gas and dust. Solar radiation pressure, exerted by photons from the Sun, pushes the dust particles away, forming a curved dust tail. Simultaneously, the solar wind, a stream of charged particles (protons and electrons) emitted by the Sun, interacts with the ionized gases from the comet, pushing them directly away from the Sun to form a straight ion tail. Both these forces originate from the Sun and act radially outwards, thus ensuring the comet's tail always points away from the Sun, regardless of the comet's direction of motion.
Incorrect Options
Option 1: Centrifugal force acts on the entire comet system as it orbits the Sun. While it plays a role in orbital mechanics, it is not the primary mechanism responsible for the formation or consistent direction of the comet's tail. The tail material is pushed away by solar radiation pressure and solar wind, which are non-gravitational forces acting specifically on the ejected gas and dust, not solely by centrifugal force on the lighter mass.
Option 2: The gravitational attraction from distant stars is negligible compared to the Sun's influence and the non-gravitational forces (solar radiation pressure and solar wind) that shape a comet's tail. The direction of the tail is determined by forces originating from the Sun, not by the gravitational pull of other stars.
Option 4: The statement that "the tail of the comet always exists in the same orientation" is incorrect. The tail's orientation continuously changes relative to the comet's direction of motion as the comet orbits the Sun. It consistently points away from the Sun, meaning its absolute orientation in space changes as the comet moves around its orbit.