Answer:
The correct answer will be - a time frame or age period
Step-by-step explanation:
Developmental psychology is the scientific study which deals with the study of why and how human beings change over time. This branch of study is also known as Lifespan Development.
The development period when one is an infant then turns into an adolescent and then into a middle-aged person, these all are the stages of the biological and chronological ages. The difference in these phases of the biological age represents a time frame or age period in which various features of the human's changes.
Thus, a time frame or age period is the correct answer.