What colour is generally formed by mixing red and blue primary colours?

Correct answer: Violet

The governing concept is the RYB traditional pigment colour wheel. When red and blue primary paints are mixed, they generally produce violet, a secondary colour. Orange comes from red and yellow, while green comes from yellow and blue; yellow itself is one of the starting primary colours rather than the product of this pair. Since the question concerns paint pigments, not additive light, option C is the unambiguous answer.