Opportunity cost, also known as alternative cost. Any decision must make a certain choice, and the highest value in the choice that is discarded is the opportunity cost of this decision. Based on the above definitions, which of the following is that is not opportunity costs? ['Xiao Li rented out his free house to his classmate Xiao Sun.', "Zhao spent all his holidays studying in the library and didn't go out to play.", 'Xiao Wang did not report to the university after receiving the admission notice, but chose to work in Guangzhou.', 'Boss Qian closed his garment processing factory and bought all the money to buy a commercial house in anticipation of appreciation.']