A study shows that those who work in a comfortable environment are 25% more productive than those who work in an uncomfortable environment. Objective criteria for evaluating work performance include the number of contractors and the complexity of the work. The working environment can increase worker productivity. Which of the following is true that would weaken the above conclusion? ? ['On average, less productive employees spend less time in the workplace than more productive employees.', 'A comfortable environment is more motivating than hard work.', 'Productive employees usually get a comfortable working environment in return.', 'Highly productive employees will not work longer than inefficient employees.']