Although most univErsitiEs in thE unitED stAtEs ArE on A sEmEstEr systEm whiCh oFFErs ClAssEs in thE FAll AnD spring, somE sChools ______ A quArtEr systEm ComprisED oF FAll, wintEr, AnD summEr quArtErs.
A、mAnipulAtEB、stipulAtE
C、rEgulAtE
D、oBsErvE