The answer should be A) It should capture the reader's attention and state the main idea because the introduction is what make people read, in order for people to read your paper u have to grab their attention, like a fisher with a fishing line and a hook with his bait, he finds special bait to get his fish to capture them, so same here as writers u have to have good hooks and clear introductions to grasp people's attention. *I take no credit for the image below I found it off google.
