In an online class, the teacher writes content in dark blue on a black background. Which improvement would be most effective?

Correct answer: Use light text with strong contrast

The governing concept is contrast and legibility. Dark blue placed on black has low luminance contrast, so students may struggle to distinguish the characters, especially on a screen or from a distance. Replacing it with clear light text against the dark background creates stronger contrast and improves reading, making option D correct. Darker blue, thinner letters, and a busy image would reduce readability further.