Quinn Has Spent the Afternoon Setting Up Hundreds of Dominoes

Multiple Choice

Quinn has spent the afternoon setting up hundreds of dominoes. When his brother gets home, he comments that Quinn has created an interesting clover-leaf pattern. Though Quinn wasn't aware he was doing this, he is able to see the pattern when his brother points it out. Which Gestalt principle are both boys using?

A) Similarity
B) Figure-ground
C) Concentrics
D) Continuity