Hello!! Your answer would be A - 3. The Great Plains/Interior Plains expands from lower Canada to upper/middle of the United States. #1 would be Cordillera, #2 would be the Arctic Lands, #3 would be the Interior Plains, #4 looks best like the Canadian Shield, #5 would be the St. Lawrence Lowlands, and #6 would be the Appalachian Region. The Hudson Bay Lowlands would be at the bottom of the Hudson Bay and the James Bay. I hope I helped!! Have a great day. :)