B is the correct answer. Infancy typically refers to the period immediately after birth until a young human starts walking, from which point 'toddler' becomes the term - referring to their way of walking. During toddlerhood, young humans get more confident walking and start choosing other methods of movement, for example skipping. They also start to learn simple concepts like shapes, colours, and so on. Early childhood encompasses both infancy, toddlerhood and later years after toddlerhood - this is, therefore, also a correct answer.