Which of the following countries has the longest coastline in the entire world?

Introduction / Context:
Coastline length is an important geographical fact that reflects how much of a country's territory borders the sea or ocean. This question checks general knowledge about world geography and specifically which country has the longest total coastline. Knowing such facts helps in understanding trade routes, climate, marine resources, and strategic maritime importance.

Given Data / Assumptions:

• The question asks for the country with the longest coastline in the world.
• Options provided are Canada, Norway, Russia, and Greenland.
• We assume coastlines are measured using commonly accepted international datasets, even though exact length can vary with different measurement methods.

Concept / Approach:
The length of coastline is calculated by summing all coastal segments of a country. Due to the fractal nature of coastlines, different methods give slightly different numbers, but the relative ranking of countries remains stable. Canada has a highly indented coastline with numerous islands and Arctic archipelagos, which greatly increase its total coastal length. The conceptual approach is to recall these rankings rather than compute raw distances.

Step-by-Step Solution:
Step 1: Recall that countries with many islands and irregular shorelines tend to have very long coastlines. Step 2: Canada borders the Atlantic, Pacific, and Arctic Oceans and includes large island groups such as the Arctic Archipelago. Step 3: Norway and Russia also have long coastlines, but their total lengths are significantly less than Canada's when all inlets and islands are counted. Step 4: Greenland is a large island territory, but it is not a sovereign country and its coastline, while long, still does not exceed that of Canada. Step 5: Therefore, among the given options, Canada has the longest coastline in the world.

Verification / Alternative check:
Standard reference sources on geography, including international encyclopedias and statistical compendiums, consistently list Canada as having the longest coastline, usually quoted as more than 200,000 kilometers. Norway, with its fjords, and Russia, with extensive Arctic and Pacific coasts, also feature prominently but rank lower than Canada. This cross-check confirms that the correct answer is Canada.

Why Other Options Are Wrong:
Norway: Norway has an extremely jagged coastline with many fjords and islands, but its total length is still less than that of Canada.
Russia: Russia spans a huge area, yet its coastline is shorter than Canada's because it has fewer large archipelagos and less coastal complexity in comparison.
Greenland: Greenland has a long coastline but is a territory of the Kingdom of Denmark and does not surpass Canada's coastline in length.

Common Pitfalls:
Students sometimes confuse land area with coastline length and may assume Russia must have the longest coast because it is the largest country by area. Others may think of Norway due to its famous fjords, or Greenland because it is a giant island. It is important to remember that Canada's combination of three ocean coasts and numerous islands makes its coastline uniquely long.

Final Answer:
Therefore, the country with the longest coastline in the world is Canada.