Correct Response: A. A deep-ocean trench is an offshore environment with very still water. Shale is a sedimentary rock that forms by compaction of fine-grained sediments that have slowly settled out of very slow moving water. Of the response choices, shale is the only likely sedimentary rock that would be expected to have formed in such a depositional environment. Sandstone (B) is typically associated with higher energy depositional conditions such as beaches and rivers. Breccia (C) is a sedimentary rock composed of angular fragments cemented together with finer grained sediments and is most often associated with high-energy depositional environments, such as desert flash floods or sheet wash deposits from steep hillsides. Limestone (D) is a carbonate sedimentary rock that most often forms from the shells of marine organisms in relatively shallow and warm marine environments and is not associated with deep-ocean trench depositional environments.
