B. The teachers at school are having a dinner to which you are invited. It will be at 7 P.M. on June 17 and will cost $7.50 a person.
This is the best summary of the invitation because it includes the most important details from the original message, such as the date, time, location, and cost of the dinner, as well as the fact that it is being hosted by the teachers at Newtown Elementary School. It also mentions that you need to let the teachers know by a certain date if you plan to attend, which is an important part of the invitation. Option A is too brief and only mentions the cost and the need to respond by a certain date, while options C and D are not accurate summaries of the invitation.