A recurring sequence of thick, thin, thin lines is an example of what?

Correct answer: Complex alternating rhythm

The smallest repeating unit is thick–thin–thin, and this unit returns in the same order. Because the pattern combines contrasting line qualities in an organised repeated sequence, it creates a complex alternating rhythm. Progressive rhythm would show a gradual change, such as lines steadily becoming thinner or larger. Random rhythm would lack a predictable unit, while flowing rhythm would suggest continuous directional movement rather than this fixed alternation. Therefore, option B is correct.