💡 Detailed Explanation
The correct choice is Option 3: 'Fill in name and address on the guest register.' The hotel clerk explicitly directs the sequence: 'では、まずこちらの宿帳に、お名前とご住所、お電話番号のご記入をお願いいたします' (Well, first, please write your name, address, and telephone number in this guest register). Showing the passport (Option 1) and getting the key (Option 4) happen after she completes the form. Thus, Option 3 is correct.