In which direction does violet generally shift when more red is added?

Correct answer: Warmer and reddish

The governing concept is colour bias and relative temperature. Violet is a mixture of red and blue; when more red is added, the balance shifts toward red-violet. It therefore appears redder and relatively warmer, making option A correct. More blue would create a cooler bluish violet. Yellowish green and neutral grey would require different pigments or a complementary neutralising mixture, neither of which is described in the question.