Which mixture is more likely to produce a purer blue-violet?

Correct answer: Bluish red and reddish blue

The governing concept is pigment bias in subtractive colour mixing. A blue-violet needs red and blue pigments that lean toward each other: the red should be bluish and the blue should be reddish. This minimises yellow or green contamination, so less complementary absorption dulls the result. Yellowish red and greenish blue introduce unwanted biases, while the other mixtures do not directly form a clean blue-violet. Thus option D is correct.