If a poster-colour title has an attractive colour but disappears into the background what should be changed?

Correct answer: Value or hue contrast between title and background

The governing design principle is contrast for legibility. A title becomes visible when its value or hue is sufficiently different from the background, allowing the letters to separate clearly at a glance. Therefore, option D is correct. Changing brush size may alter stroke width, while paper thickness and the colour name do not create visual separation by themselves. The designer should test a stronger light-dark or warm-cool contrast without sacrificing harmony.