From the point of view of the private firm foreign investment will be profitable only if

A、    net-of-taxreturnsabroadexceednet-of-taxreturnsathome.
B、    Grossreturnsabroadexceednet-of-taxreturnsathome.
C、    net-of-taxreturnsabroadexceedgrossreturnsathome.
D、    Grossreturnsabroadexceedgrossreturnsathome.