A relief sculpture is

Relief is a sculptural technique where the sculpted elements remain attached to a solid background of the same material. The term relief is from the Latin verb relevo, to raise. To create a sculpture in relief is to give the impression that the sculpted material has been raised above the background plane. What is actually performed when a relief is cut in from a flat surface of stone (relief sculpture) or wood (relief carving) is a lowering of the field, leaving the unsculpted parts seemingly raised. The technique involves considerable chiselling away of the background, which is a time-consuming exercise. On the other hand, a relief saves forming the rear of a subject, and is less fragile and more securely fixed than a sculpture in the round, especially one of a standing figure where the ankles are a potential weak point, especially in stone. In other materials such as metal, clay, plaster stucco, ceramics or papier-mâché the form can be just added to or raised up from the background, and monumental bronze reliefs are made by casting.

Explanation:

answer; i believe the correct answer is "he who gladly serves"

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.