The correct option is (b).
Explanation
The Earth is a celestial body that does not emit its own visible light. It receives light and heat energy from the Sun (Insolation). The spherical shape of the Earth and its rotation on its axis determine the distribution of this light, resulting in the cycle of day and night.Statement 1 is Incorrect: The Earth does not produce its own light. Unlike stars (such as the Sun), planets are non-luminous bodies. The Earth is visible from space because it reflects sunlight. Its spherical shape is a physical characteristic but is not a cause for light production.
Statement 2 is Correct: Due to the spherical shape of the Earth, only one half of it faces the Sun at any given time. The portion facing the Sun receives light and experiences day. The boundary separating the lit half from the dark half is known as the Circle of Illumination.
Statement 3 is Incorrect: The portion of the Earth facing away from the Sun is blocked from direct sunlight and experiences night, not continuous twilight. Twilight is a transient phenomenon occurring during the transition between day and night (dawn and dusk) when the Sun is just below the horizon, scattering light in the atmosphere. It does not characterize the entire dark hemisphere.
Key Takeaway: The Earth is a non-luminous planet that receives light from the Sun. Its spherical shape ensures that only half the planet is illuminated at a time (Day), while the other half remains in shadow (Night).