Answer:
Correct answer to the question is: Kazakhstan, Mongolia and China
Step-by-step explanation:
As we all know Russia is the largest country of the world, and thus borders with many other countries. To the south Russia borders Georgia, North Korea, Azerbaijan and many countries, but the largest ones are:
China - 9.596.961 km2
Kazakhstan - 2.724.900 km2
Mongolia - 1.564.116 km2
All other countries have less than one million square km.