When demand for a factory's products is high, more money is spent at the factory for safety precautions and machinery maintenance than when demand is low. Thus the average number of on-the-job accidents per employee each month should be lower during periods when demand is high than when demand is low and less money is available for safety precautions and machinery maintenance. Which of the following, if true about a factory when demand for its products is high, casts the most serious doubt on the conclusion drawn above? ['Its management hires new workers but lacks the time to train them properly.', 'Its management sponsors a monthly safety award for each division in the factory.', 'Its employees ask for higher wages than they do at other times.', 'Its old machinery is replaced with modern, automated models.']