A parcel delivery company calculated that nearly 10% of its drivers

A parcel delivery company calculated that nearly 10% of its drivers’ time was spent waiting to make left turns across busy traffic. During that time, the engines on the drivers’ trucks were idling, wasting fuel while not advancing the vehicle or delivering packages. In an effort to reduce labor costs by making drivers’ time more efficient, the company recalculated its routes to involve only right-hand turns. Over the subsequent year, the company saw its fuel costs decrease by over 10%, a savings that its operations team attributes to the route recalculation.

Which of the following, if true, would most weaken the operations team’s assertion that the fuel savings can be attributed to route recalculation?

A) Some drivers’ routes were several miles longer after the route recalculation than before it.

B) The cost of a gallon of fuel dropped by nearly 20% in the year after the route recalculation.

C) The route recalculation led to a significant reduction in the number of accidents caused by the company’s vehicles.

D) The fuel savings over the first year were largely offset by the cost to train drivers to handle their new routes.

E) During the first month of the new routes, the average mileage per route increased as drivers missed stops and had to circle around to return to the route.