【正确答案】 A

【答案解析】[听力原文] Welcome to the World Inventors' Conference. First off, I'd like to acknowledge those of you who traveled great distances to be with us today. We trust that the trip will be worthwhile. I'm pleased to announce that we have our best turnout for this event including participants from over thirty five different countries. Throughout the next few days, hundreds of companies will set up booths in the Elm hall to present the latest inventions. Please feel free to head over to the Elm hall at your convenience. We will also be serving snacks and beverages in the lobby for those who are interested. [解析] 通过文章开头部分出现的Welcome to the World Inventors' Conference.～to be with us today.可以得知，大会主持人向各位与会者表示欢迎。

【正确答案】 B

【答案解析】[解析] 问题是询问说话者为何高兴，通过文章中间部分出现的I'm pleased to announce that～from over thirty five different countries.可以得知，因为与会者众多，所以说话者很高兴。

【正确答案】 A

【答案解析】[解析] 文章的最后部分出现we will also be serving snacks and beverages in the lobby for those who are interested用light refreshments代替snacks和beverages，故选项A为正确答案。