Visual rhythm breaks in a group of parallel lines painted with poster colour. What should be checked first?

Correct answer: Regularity of spacing and line thickness

The governing concept is visual rhythm through repeated, consistent elements. In parallel-line work, rhythm depends first on an even interval between lines and reasonably uniform line thickness. If spacing or width changes unexpectedly, the eye notices a break in the sequence. Paper brand, water temperature, and palette size may affect general working conditions, but they do not directly explain a broken repeated pattern. Therefore option A should be checked first.