The best evidence that there is a critical period for language acquisition the fact that?

The best evidence that there is a critical period for language acquisition is the fact that children who are exposed to a second language before the age of 6 or 7 typically acquire it with a native-like accent, while those who are exposed after that age typically do not.

It is generally believed that the critical period for language acquisition ends at puberty. This is because after puberty, the brain undergoes a number of changes that make it less able to learn new languages. These changes include the pruning of synapses, a decrease in the number of neurons, and a decrease in the production of neurotransmitters.