The cytoplasm is the fluid present in the cell. In the cytoplasm all the membrane bound organelles are present and the cytoplasm is present throughout the cell. It is mostly fluid and in a diagram, it is denoted as an empty space. So, the indicated part in the given picture is the cytoplasm of the cell.
Explanation: A stream terrace basically forms through this process– Temporary base level is eliminated; the stream downcuts upstream from the old temporary base level, and the former floodplain is left well above the present elevation of the stream.
