An online retailer that makes its deliveries through a private shipping company has determined that, unlike before, now it can profitably begin making deliveries seven days a week, not just six days a week. Delivering a given number of shipments within a narrower window of time tends to be more cost effective, because, on average, delivery trucks will be able to exploit economies in their driving routes and will incur lower average shipping costs per dollar of delivered goods per hour. Nevertheless, the retailer expects profits to rise with the change.
Which of the following, if true, provides the best reason for the expectation?
【选项】
Due to trends in retail, the average volume occupied in a delivery truck by a single shipment has increased.
选项是否正确？