Which sentence from paragraph 9 best develops the author's point of view? Select the correct answer.
Brooding, which is known among cognitive scientists as morbid rumination, is a mental state familiar to most of us,
in which we can't seem to stop chewing over the ways in which things are wrong with ourselves and our lives. This
broken-record fretting is not healthy or helpful. It can be a precursor to depression and is disproportionately
common among city dwellers compared with people living outside urban areas, studies show.