When demand for 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... Which of the following casts the most serious doubt on the conclusion drawn above?
A. Employees demand for higher wages than they do at other times.
B. Authority hires new workers but lacks the time to train them properly.
C. Employees are less likely to lose their jobs than are at other times.
D. Authority sponsors a monthly safety award for each division in the factory.
