In response to mounting public concern, an airplane manufacturer implemented a program with the well-publicized goal of reducing by half the total yearly amount of hazardous waste generated by its passenger-jet division. When the program began in 1994, the division' s hazardous waste output was 90 pounds per production worker; last year it was 40 pounds per production worker. Clearly, ttherefore, charges that the manufacturer' s program has not met its goal are false. Which of the following is an assumption on which the argument depends? ['The number of production workers assigned to the passenger-jet division was not significantly less in 1994 than it was last year.', 'The average number of weekly hours per production worker in the passenger-jet division was not significantly greater last year than it was in 1994.', 'Since 1994, other divisions in the company have achieved reductions in hazardous waste output that are at least equal to that achieved in the passenger-jet division.', 'The amount of nonhazardous waste generated each year by the passenger-jet division has not increased significantly since 1994.']