In the presence of external economies of scale, trade
A.
will unambiguously worsens welfare in both countries.
B.
will unambiguously worsen welfare in the exporting country and improve welfare in the importing country.
C.
will unambiguously improves welfare in both countries.
D.
will unambiguously improve welfare in the exporting country and worsen welfare in the importing country.
E.
may or may not improve welfare in both countries