Why is limited use of red-violet effective in a night scene?

Correct answer: It creates subtle warm contrast and depth among the dominant blue-violet hues

Red-violet is relatively warmer than blue-violet. When used sparingly in a night scene, it introduces a small warm accent among dominant cool hues, creating subtle contrast, depth, and visual interest while preserving the calm nocturnal mood. Thus A is correct. Excessive red-violet could weaken the cool unity. B is not the best explanation because warm colours generally advance rather than recede; C and D are false because the accent neither removes all contrast nor automatically turns shadows black.