Terms that are asked to be used in the response are bolded;
Ocean ridges and trenches are related in a few ways. One of the ways is being created from the movement of tectonic plates on the mantle when they diverge and converge. When tectonic platesdiverge they "pull apart" and create trenches. When they converge they "push together" and create ridges, subduction happens here. The tectonic plates move on the mantle of magna from convection currents creating these different boundaries.
Have a nice day!
<em>Note: Please keep in mind that if you would like to use my work you must reword it or give a proper citation, thanks.</em>
I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly.
