When will different weights of the same typeface remain harmonious?

Correct answer: When the type family remains the same and weight creates hierarchy

The governing concept is typographic harmony: related letterforms should work together as one visual system. Using one type family preserves consistent structure, while light, regular and bold weights can create a clear hierarchy between labels, headings and body text. Option B is correct. Unrelated colours, random directions or unplanned size changes would disrupt consistency and make the design harder to read.