You can start by repeating the question like if it was "where does water come from?" then you ask: where does water come from so add a little introduction and answer and it becomes: Where does water come from? water comes from this and that and that and this but also this and that and it all does this and that while that and this is happening
The correct answers are: Helmer knows that there is a piece of mail from Krogstad in the box. Nora looks at her watch and tells herself she has 31 hours to live. Helmer thinks that Nora is nervous and dismisses her pleas about the mail.
Indeed, the text is both very explicit and implicit. Helmer’s character explicitly declares that he thinks a letter from Krogstad is inside his locked mailbox. Nora is very explicit about having only 31 hours to live since Helmer will discover the latter and she will take her own life due to that.
The implicit part is that Helmer, who is a very condescending chauvinist, does not take her nervousness seriously and treats her as a child that is going through one of her phases. He will read the letter whenever he wants and the only way Nora is able to keep him from doing that is to keep him busy with her until the deadline arrives.
The correct answer would be A because you need a comma in between the <em>A </em>and <em>S</em>
