Residents in a certain community have a good manner of helping others. In this community, everyone who has helped Lao Liu, Lao Zhang has helped; a person, as long as one person has not helped him, Lao Zhou has helped him. Soon after Wang Xin moved in, he hadn't helped anyone else. Based on the above statement, which of the following can be derived? ['Lao Zhou has not helped Lao Zhang.', 'Lao Zhou has not helped Pharaoh.', 'Lao Liu and Lao Zhang helped each other.', 'Lao Zhang and Lao Zhou helped each other.']