Mind refers to the sum of the ability of people to deposit and store known things through biological responses (brain information processing) to achieve a certain desire. Which of the following is mental? ['The first cry after the baby is born.', 'Xiaoling ’s pet dog Lingling keeps calling as soon as he sees someone in the house.', 'Xiaomin just learned to walk, she cried when she saw the cat, and kept calling her mother.', 'The three pups domesticated by Xiao Xu, a panda trainer, drool every time they hear the bell.']