Which hypothesis suggests that if grammatical rules are acquired, both written and spoken language skills will follow?

The Monitor Hypothesis posits that the ability to produce correct language, whether spoken or written, is influenced by the conscious understanding and application of grammatical rules. This hypothesis suggests that when learners acquire grammatical structures, they can use these rules to monitor and self-correct their language use in communication. Essentially, it suggests that a strong grasp of grammar allows for improved skills in both writing and speaking, as learners become more adept at manipulating the language they've learned.

In terms of the other hypotheses, the Input Hypothesis focuses on the importance of comprehensible input in language acquisition, suggesting that learners progress when they understand language slightly above their current proficiency level. The Acquisition-Learning Hypothesis distinguishes between acquiring language naturally and learning about language through formal instruction, but it does not specifically tie grammatical understanding to enhancing spoken or written skills. The Output Hypothesis emphasizes the role of output in language learning, proposing that producing language helps to solidify and develop language skills, yet it does not directly link grammar acquisition to subsequent language proficiency in both spoken and written forms as strongly as the Monitor Hypothesis does.