AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
Option A is correct. Both A and R are true, and R is the correct explanation of A. Newton placed a second prism inverted relative to the first; it recombined the dispersed colours, and white light emerged from the other side.
Source: Chapter 10, Section 10.4 — Dispersion of White Light by a Glass Prism
The passage explicitly states that Newton placed a second identical prism in an inverted position, and white light emerged from the other side. The reason — that the second prism recombines the dispersed colours — directly and correctly explains why white light re-emerges. So both statements are true and causally linked, making Option A the right choice.