To determine the tone of the writer in the given statement, we need to analyze the words and phrases used. In this case, the writer is saying "Please do eat the last piece of pizza" and follows it up by saying "I haven't had any yet, but you should definitely have a third piece." Based on this, we can conclude that the writer's tone is sarcastic because they are pretending to be generous by telling the reader to eat the last piece of pizza, even though they actually want it for themselves. Therefore, the correct answer is "sarcastic."
