The sentence in question: その理由を聞いてみると。
For full context: https://www3.nhk.or.jp/news/web_tokushu/2018_0521.html?utm_int=news_contents_tokushu_004
My attempt at translatino: "I tried to learn of the reasons."
The sentence itself seems fairly simple to me, however I have no clue what to do with this "trailing" と ^^