Creative labor: refers to an unprecedented labor method that requires the use of the creativity of laborers, as opposed to repetitive labor (referring to labor that only needs to be performed in accordance with certain procedures and methods). Which of the following is creative labor? ['Mom tells her son in high school to go to the supermarket to buy a bag of salt again.', 'Cao Xueqin in the last stage of his life, with tenacity and perseverance, completed the great book "A Dream of Red Mansions" after ten years.', 'Xiao Wu completed all ten addition calculations at once in accordance with the method taught by the teacher.', 'After the staff puts things into the box according to the regulations, the box is sent to a machine 2 meters away for sealing.']