Which tertiary colour is formed by mixing red and orange?

Correct answer: Red-orange

On the traditional colour wheel, red is a primary colour and orange is the adjacent secondary colour made from red and yellow. Mixing these neighbouring colours produces red-orange, so option B is correct. Yellow-orange comes from yellow and orange, red-violet from red and violet, and blue-green from blue and green. The name of the tertiary colour normally combines the names of the two colours mixed.