Executives at Leonesse Cellars, a premium winery in Southern California, were surprised to learn that shipping wine by sea to some cities in Asia was less expensive than sending it to the East Coast of the United States, so they started shipping to Asia. Source: (David Armstrong, "Discount Cargo Rates Ripe for the Taking," San Francisco Chronicle, August 28, 2005). Because of the large U.S. trade imbalance with major Asian nations, cargo ships arrive at West Coast seaports fully loaded but return to Asia half to completely empty. Use the concept of opportunity cost to help explain the differential shipping rates.
Shipping wine to Asia is less expensive than transporting wine to the East Coast because:________.
A. the price a shipping firm could have earned by transporting other cargo is high.
B. the value of the next best use of ships from the West Coast to Asia is low.
C, the cost of ships in sea transportation is a sunk cost.
D. the incremental cost of another shipment to Asia is decreasing.
E. the value of wine to consumers in Asia is higher than on the East Coast.

The opportunity cost of someone using cargo ships seems to be minimal like this since the container ships returning to Asia again from ports and airports including its West Coast have either been nearly empty or fully empty, which indicates that although the wines weren't sent throughout themselves, that room would stay empty even if there's no possible effective use of another room.
Cargo Owners would be prepared to offer certain rooms to either the winery to sell the products to Asia at a somewhat cheaper cost and if they do not provide it, the room is already vacant, there is no reasonable appropriate use of such a space upon on cargo vessel.

Some other equivalents offered are not relevant to something like the scenario given. So, the solution is indeed the right one.