Niagara Falls is a great tourist ______ drawing millions of visitors every year.选项:a、attention b、 attraction c、 appointment d、 arrangement选哪个?为什么?请翻译?

问题描述:

Niagara Falls is a great tourist ______ drawing millions of visitors every year.
选项:a、attention b、 attraction c、 appointment d、 arrangement
选哪个?为什么?请翻译?