Which combination is correct for making the foreground appear near and the background appear distant?

Correct answer: Warm colours in foreground and cool colours in background

The governing concept is colour-based depth creation. Warm colours such as red, orange and yellow tend to advance visually, while cool colours such as blue and blue-green tend to recede. Placing warm colours in the foreground and cool colours in the background therefore supports the intended near–far relationship. The grey or black-only choices remove the warm–cool contrast and do not provide this specific colour cue for depth.