The answer would be the first one because it sounds formal where as the other ones are less formal and sound as if you are talking to a friend
They do an in depth study about whatever they are investing in and make sure it's something they want to throw their money at.
Answer: The purpose of this sentence in the second paragraph is to show that Gregor is not dreaming.
Explanation: Gregor recognizes that this is his own room with his own belongings.
Answer:
Rereading helps you better understand the text and can possibly go through what you missed. While reading on can help you get more context and make connections on what you just read.
