Based on the given sentences above, the one that is punctuated correctly is the second sentence: She sends an email therefore, to her instructor and advisor. What makes the first sentence incorrect is that, it has no period at the end of the sentence. Hope this answer helps.
The pre in preview means that the students were able to see the movie before it actually came out.
I believe it’s answer choice A. Even though it does say that they are estimated to spend 155 billion dollars, they are asking questions related to spending money, such as where they shop and what books they like and so on.
