What does the underlined word "them" in PARAGRAPH FIVE refer to?

A
考查指代题。题干：第五自然段中的"them"指代的是什么。第五段中them出现在最后一句，具体的指代内容应该在真前面，前面一句高提到"…American practice of requiring propertydevelopers to provide a certain number of parking spaces for every building..."美国人惯常的做法是让开发商在每幢建筑都留有一定的停车空间，由此可知 "them"指的是A，parking spaces停车空间。