The answer that you have given here is clearly correct. This is rather simple to check. All you have to do is to look up (online or in your textbook) a list of the countries of the world sorted by their area. If you find such a list, you will see that Russia is by far the largest country in the world. In fact, Russia is almost twice as large as the next largest country. Russia is about 17 million square kilometers in area. Canada is the second-largest country in the world. It is just under 10 million square kilometers in area.
Therefore, you can answer this question correctly simply by looking up a list of the largest countries by area in the world.