Frictional unemployment is short-term, partial unemployment caused by normal labor movement or inevitable friction in production. According to the above definition, which of the following is frictional unemployment? ['As winter is the off-season, the tour guide Xiao Zhang was fired by the company in the name of saving money.', "Ms. Li hasn't found a new job after giving birth.", 'Liu San gave up his job in Shijiazhuang and went to Beijing to develop, but he has not found a suitable job.', 'Xiao Wanggang graduated from university and has not found a job he is satisfied with.']