Which mixture will create yellow-green instead of balanced green?

Correct answer: More yellow and less blue

The governing concept is the effect of component proportion in a colour mixture. Equal blue and yellow produces a balanced green, but increasing yellow shifts the result toward yellow-green. Thus option D is correct. More blue would make the green bluer, while green plus black creates a darker shade and does not specifically produce yellow-green. The ratio, not merely the names of the colours, determines the direction of the shift.