Thanks for the question! So if H is not on day 7, we know R can only be on days 3 and 5, for a maximum of two days. Why? Well, if H is on day 7, H goes on days 2, 4, and 6. Since H and R can’t be together, R can’t be on any of those days. A rule tells us R can’t go on day 1 or 7. So that leaves only days 3 and 5, making (E) impossible.
Hope this helps! Feel free to ask any other questions that you might have.
