Based on the scenario given, please drag and drop the correct answer in the blank:

"A store manager observes that the morale of employees in her supermarket is low. She thinks that if their working conditions are improved, pay scales raised, and vacation benefits made more attractive, morale will be boosted. She doubts, however, if an increase in pay scales would raise the morale of all employees. Her conjecture is that those who have supplemental incomes will just not be "turned on$"$ by higher pay, and only those without side incomes will be happy with increased pay, with a resultant boost in morale.

The type of research problem is

The dependent variable is

One of the independent variables is

The unit of analysis is