Forco, a Brazilian corporation, is engaged in the United States trade or business of selling widgets. It has a North Carolina plant and a North Carolina sales office. To what extent will the income described below be considered effectively connected to Forco's United States trade or business?

a. Income from the sale of widgets to United States persons, with title passing in the United States.

b. Income from the sale of machinery used by Forco at its North Carolina plant.

c. Gain from the sale of machinery used by Forco at its North Carolina plant.

d. Interest income from bank deposits of excess cash made by Forco's United States branch.

e. Forco also purchases decorative cups in Brazil from unrelated parties, which it sells worldwide, but it does not have sufficient activity in the United States for it to constitute a United States trade or business. Will income from the sale of decorative cups to United States customers be considered effectively connected income?