During first language acquisition, at which stage do children frequently make errors due to overgeneralization and undergeneralization of linguistic rules?

Between 12 to 18 months of age, children begin to produce a variety of recognizable single-unit utterances. This period, in which single terms are uttered for everyday objects, is called the:

Read the following statements: Assertion (A): Delaying the learning of languages in the early years makes it more difficult for children to acquire new languages. Reason (R): Early years of the child are sensitive periods for language acquisition. Choose the correct option.