What is the basis for placing violet between red and blue on the colour wheel?

Correct answer: It is formed by mixing red and blue

The governing concept is the relationship between primary and secondary colours on a traditional colour wheel. Red and blue are mixed to produce violet, so violet is placed between those two component colours. Complementary colours normally lie opposite one another, not between both colours. Violet is not more primary than red or blue, and mixing all light colours is unrelated to this paint-colour arrangement. Thus, option A is correct.