thereule
I came up with reasoning that now very less containers are arriving in country X compared to times before , so whatever number of containers they would be filled quickly.
Yes, but exporters do not have enough containers to meet demand. That's why they've experienced lower revenues, lost orders, etc. The containers are LEAVING Country X quickly, but, because of choice (B) along with a reduction in imports, the containers aren't coming back to Country X quickly enough.
thereule
Whereas for D I assumed there is no goods left to export as local consumers are consuming all of it, that's why exporters revenue would decline.
We can't assume that an increase in purchasing in Country X would cause a decrease in what's available to export. It's possible that consumers are purchasing items that are not a significant source of exporter revenue. It's also possible that possible that there is plenty of supply to meet the increased demand in Country X in addition to overseas demand.