All of the athletes lined up in the park this afternoon were waiting to participate in a charity run. Blake, Tina, and Sara had all signed up to participate in the charity run. No professional runners would sign up to participate in a charity run. If the statements above are true, which of the following must also be true? ['Blake, Tina, and Sara were the only athletes lined up in the park this afternoon.', 'Neither Tina nor Sara is a professional runner.', 'None of the athletes lined up in the park this afternoon had ever participated in a charity run.', 'Everyone in the park this afternoon was an amateur athlete.']