The MMT classification of exports as a cost means
Answer: (c) The resources that are embodied in exports are lost to the nation and are, instead, used by foreigners to enhance their material prosperity.
Answer: Option (c)
Nations trade to expand their consumption possibilities.
In a world where we produce to consume, receiving goods and services is better in real terms than sending them elsewhere.
In that context, MMT characterises exports as a cost and imports as a benefit to a nation.
Exports require the nation incur an opportunity cost by sending real resources (embodied in products or raw) to foreigners which could be used locally.
Conversely, imports represent foreigners giving up their real resources (embodied in products or raw), which are then enjoyed by the importing nation.
Accordingly, external deficits (imports greater than exports) mean that a nation enjoys a higher material living standard.
Running external surpluses (exports greater than imports) effectively means that the nation is depriving its citizens of a higher material standard of living. They are working too hard, being paid too little, and/or under consuming.
Clearly, a nation that merely gives up material resources and gets nothing in return would be making itself poorer in material terms.
And certainly, the history of colonial nations is riven with examples of resource plunder from colonial masters.
That exports are a 'cost' suggests the motive to export.
The 'cost' is incurred to generate benefits - to enhance the material prosperity of the nation.
One reason that would lead a nation to relinquish access to its own real resources would be to get other real resources that it desires from other nations through trade.
Which means the export cost is best considered as an investment in generating an increased capacity to import.
The real terms of trade for a nation are defined in terms of what exports are required to acquire imports. A trade deficit is a sign that the real terms of trade are working in favour of the deficit nation.