Which option gives the most appropriate temperature classification of primary colours?

Correct answer: Red and yellow warm and blue cool

The governing concept is colour temperature, a visual classification associated with warmth or coolness rather than physical temperature. In the common traditional classification, red and yellow are warm colours, while blue is cool. Individual pigments can show warmer or cooler biases—for example, a blue tending toward violet may feel warmer than a greenish blue—but that nuance does not change the general answer. Therefore, option A is correct.