More than half of all European countries are bilingual. This is due to, mostly, the fact that all of its countries in general are near to each other. Thus, European countries are more multicultural. For example, Switzerland has four official languages, just like Belgium and Luxembourg, among others.
Besides, and because of the European Union among other reasons, the native inhabitants of Europe have free unlimited access to other countries with no visa needed, which allows them to move freely from one place to the other, encouraging, thus, the acquisition of different languages.
Finally, there is also a huge demand of a proficiency in foreign languages for young people in order to get jobs.
So, we can conclude that the correct answer is C: Bordering European countries share close economic and cultural ties.