The correct answer is d: brick. "Functional art" refers to an object that has a functional, everyday purpose, but is being used instead as an aesthetic artwork. Essentially, "functional art" is turning an object that wouldn't be considered conventional art (like a painting) into an aesthetic piece. Since a brick has a functional purpose for building, it can thus be classified as functional art. The other possible answers, a stone, a flower, and a garden, would not be considered forms of functional art because they don't serve everyday purposes. For example, we don't particularly need a flower to carry out our daily activities.