If an artist gives all shapes the same colour but makes one shape very large which contrast is mainly created?

Correct answer: Size contrast

The governing concept is contrast through size or scale. Since every shape has the same colour, colour is not the changing element; the important difference is that one shape is much larger than the others. That difference makes it visually prominent, so option A is correct. Option B would require different colours, option C would require different surface qualities, and option D would require warm–cool colour differences.