病院の中で大きい声で話し___いけません。
Q. Which completes the prohibition 'you must not talk loudly'?
Translation
You must not talk loudly inside the hospital.
Explanation
Prohibition is te-form + はいけません: 話してはいけません. 〜てもいけません is not a standard pattern — ても means 'even if', while てはいけない is the fixed 'must not' construction.