Which type of lamp emits a strong light with a bluish cast?

Metal halide lamps emit a bright, white light with a bluish cast. This makes them ideal for applications requiring good color rendering and visibility, such as CCTV surveillance or high-intensity outdoor lighting.

A (Sodium vapor) emits yellow/orange light.

C (Mercury vapor) also has a bluish tint but less desirable color rendering.

D (Incandescent) gives off a warm, yellowish light.