Which type of colour chart is most useful for understanding mixing proportions?

Correct answer: Ordered, labelled colour-mixture samples made in different proportions

The governing concept is recording and comparing colour mixtures systematically. A useful chart must show the same colours in different measured proportions and label each sample, such as 1:1, 2:1, or 3:1. This makes the effect of increasing one component visible and repeatable, so option C is correct. A list of names identifies colours but shows no ratios; black-and-white samples are too limited, and unlabelled shapes cannot be reliably compared or reproduced.