35.
Your Answer is
Correct Answer is C
Explanation
This sentence means that "Suzuki already knows that immersion learning is the key to children's language learning", and the word order of item C is correct.
Item A: Passive voice is an informal expression.
Item B: The error lies in the extra comma.
Item D: The fault lies in A key... cannot be placed at the beginning of the sentence as an apposition of Suzuki.