What is the best way to correct dark red that appears too black?

Correct answer: Add a little base red

The governing concept is restoring the dominant base hue in an over-dark mixture. If dark red has been made too black, adding a small amount of the original red increases the red pigment and reduces the visual dominance of black, bringing back a clearer red appearance. Therefore, option D is correct. Adding more black would worsen the problem. Green, the complement of red, could neutralise or muddy the mixture, while blue would shift it toward a purplish, cooler colour rather than correcting the excessive blackness. Add red gradually for control.