Chomsky observed that: a. some rules of grammar are present in all languages. b. all parents reinforce correct use of grammar. c. all young children master basic grammar according to a schedule. d. all grammar rules are the same across all languages.

The correct option is C: All young children master basic grammar according to a schedule

Explanation:

Noam Chomsky has been credited for his work done on universal grammar theory. In modern linguistics, this theory suggests that a specific set of structural rules are peculiar and natural to human beings, not depending on sensory experience. From the options, Chomsky observed a structural pattern or schedule in which humans use in the mastery of basic grammar.