Which evidence best supports the claim that living in a foreign country is the smartest way to learn a new language?
I really hope to spend a semester in Paris because it is the perfect place to see cultural landmarks and improve my French.
A television advertisement encourages students to purchase language study software and guarantees a forty-five percent
improvement in six weeks.
My father spent several years in Peru and learned to speak Spanish so fluently that people thought he was a native Peruvian.
Language researchers found that students who lived in a foreign country learned the new language sixty-five percent faster
than students learning at home.

I would say the last evidence. I believe one of the main reasons to live abroad is to also learn a new language, and the last evidence even says "language researches found" more people would believe it then because it comes from professionals. So it motivates people to live abroad more (and those who really want to learn a new language better).

The second one is a bit risky, because everyone is different and maybe he has a gift for learning new languages like that. For some people it would take 15 years or more. My mom lived in Germany from when she was 18 till 50 and to this day her german accent still sounds a bit french. My point is everyone is different when it comes to learning new languages, so the evidence is not very helpful.

However the last one comes from professionals, who've studied this research and know what they're talking about.

Hope this helped, and sorry my english is not the best

what is the passage