What does "putting together of dissimilar elements" refer to?

Contrast is the obvious difference between two or more different objects when they are put together or compared. A contrast is formed when things, people, places or concepts are put together or compared in order to show their differences.

Explanation:

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i would say the answer is b. zigzag lines of the leaves. i believe this is the answer because zigzag lines go in different direction while the other options like: the vertical lines of the trees, the dotted lines on the road, and the curved lines of the park benches go in one direction.