Which secondary colour is generally considered a warm colour?

Correct answer: Orange

Orange is a secondary colour made by mixing the primary colours red and yellow. Because it contains and visually relates to warm red and yellow, it is generally classified as a warm colour and often suggests energy, brightness, and activity. Therefore, option C is correct. Green and violet are commonly grouped as cool colours, while blue is a primary rather than a secondary colour. Colour temperature is a traditional visual classification, not a physical temperature measurement.