Final answer:
Physical development is lower at ages 5 and 6 compared to earlier years because children experience a slowdown in growth rate as they transition from early childhood to middle childhood. They continue developing motor skills and begin losing baby teeth as permanent teeth emerge.
Step-by-step explanation:
The body's physical development is lower at ages 5 and 6 than at any other age in the first five years of life. During early childhood, especially the preschool years from ages three to five, children experience rapid physical, cognitive, and psychosocial development. They transition from being toddlers who are just starting to walk and say a word or two, to preschoolers who can ride a bike and use upwards of 1,500 words. However, entering into middle childhood, which starts after age five, the rate of physical development slows down as children have completed most of the rapid growth characteristic of early childhood.
Once children reach age six, they continue to develop motor skills, such as riding a bicycle without training wheels, and experience improvements in agility, balance, and coordination. They also start losing their baby teeth and their permanent teeth begin to emerge. Therefore, the statement likely refers to the decrease in the growth rate that occurs as children transition from early childhood into middle childhood.