Concept: Adolescence is the developmental stage that connects childhood to adulthood.
Explanation: It usually spans from about 10 to 19 years of age.
During this time, a person experiences physical, emotional, and social changes.
Infancy is only the period from birth to 1 year old.
"Teenage" describes ages 13 to 19, but it is not the clinical term for the whole transition.
Puberty is the physical process of sexual maturation, which happens during adolescence.
This means puberty is part of adolescence, not the name of the entire stage.
Answer: A. adolescence.