Sentence 1: In the U.S., most human exposure to mercury is the result of consumption of fish contaminated with methylmercury.

Sentence 2: Residual mercury has been dumped into U.S. rivers and lakes, causing contamination.
OPTIONS:
[i] yes.
[ii] it is not possible to tell.
[iii] no.
Is this second sentence entailed by the first sentence?
[ii]