Answer:
First year and second year.
Step-by-step explanation:
The development of the infants starts from the day of the birth. The development of the baby includes the different stages and the development occurs at each month with physical and physiological changes.
During the first year of the development the child knows how to stand, walk, sit and react on the other people expressions. During the second year of the child development, the child knows about the balancing of their body and feet in the squat position.
Thus, the answer is first year and second year.