Which Canadian politician replaced Justin Trudeau as Prime Minister in March 2025 after Trudeau's resignation?

Based on current information, Justin Trudeau remains the Prime Minister of Canada. There has been no public announcement or event indicating his resignation in March 2025, nor has Mark Carney replaced him as Prime Minister. The Canadian political landscape has not seen such a transition.

Justin Trudeau has served as Prime Minister since November 2015, leading the Liberal Party to multiple election victories. Mark Carney is a prominent Canadian economist and former Governor of the Bank of Canada and the Bank of England, known for his significant roles in global finance. While Carney is a respected public figure and has been speculated as a potential future political candidate, he has not held the position of Prime Minister.

Prime Ministerial transitions in Canada typically occur through general elections or, less commonly, through a party leadership contest if an incumbent leader steps down. Any change in the country's leadership would be a major news event, widely reported and officially announced. As of the current date, the scenario described in the question has not transpired in Canadian politics.