Which pair is correct for bright orange in a split-primary palette?

Correct answer: Warm red and warm yellow

The governing concept is choosing primaries whose biases point toward the target secondary colour. Warm red and warm yellow generally lean toward orange, so mixing them introduces less opposing blue influence and preserves higher saturation. Cool red or cool yellow may carry a bluish bias, while blue itself is not the suitable partner for bright orange. Therefore option A is correct and the other pairs are less appropriate.