Final answer:
Children begin to develop a visual schema in the Schematic Stage of art growth and development, which generally occurs around 7 to 9 years of age. The correct option is c.
Step-by-step explanation:
Children begin to develop a visual schema during the cognitive development stage known as the Schematic Stage. This stage typically occurs around the age of 7 to 9 years old, following the Pre-schematic Stage. During the Schematic Stage, children start to develop and consistently use a specific set of symbols to represent different elements in their drawings, which reflects their growing ability to classify and interpret information of the world around them.
According to the theories of cognitive development by Jean Piaget, the Schematic Stage follows the earlier stages of children's art development. Thus, the correct answer to which stage children begin to develop a visual schema is (c) Schematic Stage.