Final answer:
At the international marketing stage of marketing involvement, the firm treats the world, including the home market, as one market.
Step-by-step explanation:
At the international marketing stage of marketing involvement, the firm treats the world, including the home market, as one market (option E). This means that the firm sees opportunities for sales and expansion in foreign markets, and considers them equally important as domestic market needs. The firm focuses on global operations, production, and profit expectations, rather than solely servicing domestic market needs. Planning may also involve producing goods outside the home market, making option D incorrect.