In the middle of the Sprint the product owner wants the Developers to participate in am important meeting with a group of customers. a) The Developers should strive to work on item related to current sprint. They should involve the Scrum master who can educate the product owner to defer such interruptions and if required plan them in next sprint. b) The Developers should participate in meetings since it is with customers. c) The developers should stop the Current sprint work until that meeting to ensure they clearly understand the customers concerns.