Which property of orange changes directly when the proportion of red and yellow is altered?

Correct answer: Its hue bias

Changing the ratio of red and yellow changes the direction of orange’s hue: adding more red makes it redder, while adding more yellow makes it yellower. Option A is correct. The mixture generally remains within the orange family, so its colour category does not automatically change; its complementary relationship remains broadly blue, and the medium is not determined by pigment proportion.