The statement that best describes how the child affects the development of the theme in this poem is:
by reflecting elements of the natural world
Throughout the poem, the child's experiences and reactions are used to draw parallels between the child's actions and various aspects of the natural world, such as colors on clouds, music in leaves, honey in flowers, and pleasure from the sky. The child's interactions and responses serve as metaphors or reflections of the beauty and wonder present in nature, enhancing the theme of the interconnectedness of human experience and the natural world.