Final answer:
Yifei's decision to come in late and take more days off after learning a coworker earns more for the same job is an example of 'changing work effort', a common reaction to perceived workplace inequity. This corresponds to option B in the question provided.
Step-by-step explanation:
Discovering that a coworker earns 10% more than her for the same position and duration, Yifei opts to reduce her work effort as a method for reducing perceived inequity. Such an action represents the concept of changing work effort, where an individual may adjust the amount of effort they contribute to their work in response to feelings of unjust treatment or pay discrepancies.
This behavioural change is a psychological coping mechanism to restore a sense of fairness or equity. In Yifei's case, by coming in late and taking more days off, she is effectively decreasing her input to balance the perceived inequality in outcomes (pay). This scenario exemplifies option B. Changing work effort as a method for reducing perceived inequity.