请教一道PREP题，as...as的用法。

PREP2－09

The Environmental Protection Agency frequently puts mandatory controls on toxic substances that present as little risk as one in a million chances to cause cancer.

(A) as little risk as one in a million chances to cause

(B) as little risk as one chance in a million of causing

(C) as little risk as one chance in a million that it will cause

(D) a risk as little as one chance in a million for causing

(E) a risk as little as one chance in a million for it to cause

此题答案B，没有明白这里的比较对象，还望各位指点。谢谢先！

我的理解：风险几乎是百万分之一这么少，as little as....和什么一样少。。。。