Closed-loop thinking refers to a way of thinking in which tips and responses in various ways are used to form a closed loop in each operation in the process of work and study, so as to grasp the process in real time and adjust the direction in time.
The option "When Xiao Sun first arrived at the unit, he always readily agreed to the tasks arranged by the leader and tried his best to complete them. Half a year later, when his work became busier and busier, he found that some tasks were difficult to accomplish and he no longer dared to accept them at will" does not belong to closed-loop thinking.