The correct answer is option 1: Both statements are individually true and statement II is the correct explanation of statement I.

Statement I states that the mirror used in a searchlight is parabolic. This is true because a parabolic mirror is commonly used in searchlights. A parabolic mirror has a shape that allows it to reflect light rays in such a way that they converge at a single point, known as the focus. This property of a parabolic mirror makes it suitable for use in searchlights, as it can reflect light from a source placed at the focus in a parallel beam.

Statement II explains that all rays coming from a source at the focus of a parabolic mirror are reflected as an intense parallel beam. This is also true because of the shape of the parabolic mirror. When light rays come from the focus of a parabolic mirror, they are reflected in a parallel manner, forming a concentrated and intense beam of light.

Therefore, both statements are true and statement II provides a correct explanation for statement I.