(a) A thin convex lens L of focal length $10 \text{ cm}$ and a concave mirror M of focal length $15 \text{ cm}$ are placed coaxially $40 \text{ cm}$ apart as shown in figure. A beam of light coming parallel to the principal axis is incident on the lens. The final image will be formed at a distance of (A) $10 \text{ cm}$, left of lens (B) $10 \text{ cm}$, right of lens (C) $20 \text{ cm}$, left of lens (D) $20 \text{ cm}$, right of lens