Which sedimentary rock is most likely to have been deposited in a very high-energy stream?

The appropriate answer is conglomerate. Conglomerates have large clasts embedded in a fine matrix. High energy streams are able to transport and deposit larger clasts that are gravel or pebble size. Conglomerates also indicate that the deposition of the rocks occurred in the middle course of the stream were the energy is relatively high. High energy streams flow over a steep gradient and relatively high velocity flow. Fine grained sedimentary rocks are deposited in low energy environments.

Conglomerate has a high-energy stream.