I think truism would be best because my teacher always said people your sending your big test paper to do not care about just the essay so don't talk about yourself to much only if it's opinion say I'm my opinion but not about your life
1. Nearly 1/5 of the entire ocean floor has been discovered.
2. it is important that we map our ocean floors so that we understand more about our earth. Learning more about our earth can give us more information about life in the past.
Hope this helps :)