Studies in brain science indicate that there is a "critical period" in the development of the human brain, that is, during the development of a person, a certain aspect develops fastest in a certain stage. For example, before the age of 3 is the "critical period" of the development of action The age of 1-3 is the "critical period" of language development, and the age of about 4 is the "critical period" of perceptual graphics. During this period, the brain has a strong ability to adapt and reorganize both structurally and functionally, and is vulnerable to Environmental influences, appropriate stimulation and experience during critical periods are important prerequisites for the normal development of exercise, sensation, language, and other brain functions. Which of the following uses the "critical period" theory? ['Wolf child returned to society at the age of 10 and learned simple language.', 'Deaf children with congenital hearing loss received language rehabilitation training at the age of 2 and eventually learned to speak.', 'The mother listens to music in the womb during pregnancy.', 'A gymnastics champion has been considered a gift for gymnastics at the age of 3.']