Final answer:
The purchase of a designer dress by a Canadian in France would increase Canadian GNP, as GNP measures the total income of a nation's residents, including international business activities.
Step-by-step explanation:
When Stephanie, a Canadian citizen, purchases a designer dress produced by a Canadian-owned fashion shop in France, it is assumed that Canadian consumption increases. However, this transaction would not result in an increase in Canadian Gross Domestic Product (GDP), as GDP measures the output within a country's borders, not the activities of its citizens or businesses abroad. Conversely, Canada's Gross National Product (GNP) would increase, as GNP accounts for the total income earned by a nation's residents, including international activities of its businesses and citizens. Therefore, the answer is C. Canadian GNP increases.