What is traditionally known as “the world’s longest undefended border”?
Explanation:
"The border between Canada and the U.S.A. is traditionally known as “the world’s longest undefended border,” highlighting a history of peaceful relations."
Canadian Citizenship Test gives you access to many more tests than just the one practice test available on the government website. That official sample test is good for giving you an idea of what to expect on the real test. But it can't help you prepare fully. Nor does reading the Canadian Citizenship: Our Bond material alone.