The Major Disadvantage of In-Transit Merge Compared to Drop-Shipping Is

The major disadvantage of in-transit merge compared to drop-shipping is

A) transportation costs are high because the average outbound distance to the end consumer is large and package carriers are used to shipping the product.
B) response times tend to be large because the order has to be transmitted from the retailer to the manufacturer and shipping distances are on average longer from the manufacturer's centralized site.
C) order tracking becomes harder to implement because it requires complete integration of information systems at both the retailer and the manufacturer.
D) the additional effort during the merge itself.