This question asks to identify a specific developmental stage according to V.V. Bunak's age-related periodization, defining it as the stage from birth to 20-21 years old. In developmental psychology, this broad period generally encompasses infancy, childhood, adolescence, and early adulthood. Based on common periodizations, this stage is often referred to as youth or adolescence and early adulthood, as it covers the transition from dependent childhood to independent adulthood.
According to V.V. Bunak's periodization:
The question encompasses the period from birth up to 20-21 years. Therefore, the most fitting description for this entire span, as per Bunak's stages, would be a combination of childhood, adolescence, and early adulthood. If a single term is required, and considering the upper limit of 20-21 years, it most closely aligns with the broader concept of youth which includes adolescence and the transition into early adulthood.
Answer: Юность