The forty ninth parallel, often referred to as the 49th Parallel, forms a long international boundary between which two countries?

Introduction / Context:
Lines of latitude and longitude sometimes serve as convenient political boundaries. One famous example is the forty ninth parallel north, usually called the 49th Parallel. It is widely known because it forms a long stretch of the land boundary between two large countries in North America. This question tests whether you can correctly identify those two neighboring nations.

Given Data / Assumptions:

• The boundary line in question is the 49th Parallel.
• We must name the two countries separated by this line.
• Options include pairs such as USA and Canada, North and South Vietnam, Germany and France, and Brazil and Chile.
• Only one pair matches the actual political boundary associated with the 49th Parallel.

Concept / Approach:
The approach is to recall which international border is famously aligned with 49 degrees north latitude. Geography textbooks and maps show that a large part of the land boundary between the United States and Canada is defined by the 49th Parallel, especially between the western provinces of Canada and the northern states of the USA. Other boundaries listed in the options are defined by different lines or natural features and are not associated with the 49th Parallel.

Step-by-Step Solution:
Step 1: Remember that the 49th Parallel is a line of latitude around 49 degrees north. Step 2: Recall common general knowledge facts that the United States and Canada share this latitude based boundary across the western part of their border. Step 3: Check that North and South Vietnam were historically separated roughly around the 17th Parallel, not the 49th. Step 4: Recognize that Germany and France share a boundary marked by rivers and other features, not by the 49th Parallel. Step 5: Brazil and Chile also have boundaries formed by mountains and not by the 49th Parallel, so select USA and Canada as correct.

Verification / Alternative check:
As an alternative check, recall that in many school atlases there is a labeled line at 49 degrees north crossing North America, and it is annotated as the border between the USA and Canada. In contrast, maps showing the 17th Parallel mark the historic division between North and South Vietnam, confirming that the Vietnam option is incorrect for the 49th Parallel.

Why Other Options Are Wrong:
North and South Vietnam: Historically separated near the 17th Parallel during the Vietnam conflict, not at 49 degrees north.
Germany and France: Their boundary follows rivers like the Rhine and various historical treaties, not the 49th Parallel.
Brazil and Chile: These countries are separated by the Andes Mountains and are located in the Southern Hemisphere, far away from 49 degrees north.

Common Pitfalls:
A frequent confusion is mixing up different famous parallels such as the 38th Parallel in Korea, the 17th Parallel in Vietnam, and the 49th Parallel in North America. A good revision strategy is to create a small table mapping each parallel to its associated boundary so that in the exam you can recall them quickly without mixing them up.

Final Answer:
The forty ninth parallel forms a major boundary between USA and Canada.