Terrigenous deposits are sedimentary deposits that are derived from the land and transported to the ocean by rivers, wind, or glaciers. These deposits consist of various materials such as sand, silt, clay, and organic matter.

The correct answer is option 4: Continental Shelf and Slope. This is because the continental shelf is the submerged part of the continent that extends from the shoreline to the shelf break, and the continental slope is the steeply sloping transition between the continental shelf and the deep ocean floor. These areas are the primary locations where terrigenous deposits accumulate in the ocean. The rivers, glaciers, and wind that carry sediments from the land deposit them on the continental shelf and slope before eventually sinking to the deep sea floor.

Option 1, Deep Sea Plain, is not correct because deep sea plains are generally composed of fine-grained sediments such as clay and ooze, rather than the coarser terrigenous deposits. Option 2, Ocean Trenches, and option 3, Rift Valley, are also not correct because these are deep, narrow features in the ocean that are usually associated with tectonic activity and do not typically accumulate terrigenous deposits.