Which decisive component makes yellow-green warmer than blue-green?

Correct answer: Dominance of yellow

The governing concept is hue bias, not simply lightness or darkness. Green can lean toward yellow or toward blue. Because yellow is conventionally warm, a yellow-green mixture has a warmer visual character than blue-green. Thus option A identifies the decisive component. Black or white may change value or intensity, and the value of green alone does not determine whether the hue is warm or cool.