Final answer:
The correct answer is C. Formal instruction in grammar is not a necessary condition for the normal development of communication skills.
Step-by-step explanation:
The correct answer is C. Formal instruction in grammar.
Formal instruction in grammar is not a necessary condition for the normal development of communication skills. Language acquisition occurs naturally and effortlessly during the early stages of life, and this acquisition occurs in a predictable sequence for individuals around the world. Young children master language very quickly with relative ease, even without formal instruction in grammar.
On the other hand, exposure to a rich language environment, social interaction with peers, and cognitive development and maturation are necessary conditions for the normal development of communication skills. These factors contribute to vocabulary development, sentence structure, comprehension, and overall language proficiency.