I want to know the answer to the following question:
Who erased the border in the ad?
All the background I'm provided with is that "In the 1988 federal election, the Liberals asserted that the proposed Free Trade Agreement amounted to an American takeover of Canada—notably, the party ran an ad in which Progressive Conservative (PC) strategists, upon the adoption of the agreement, slowly erased the Canada-U.S. border from a desktop map of North America.". Is that enough to answer the question?
Answer: yes