Supply curves are upward sloping is a graphical way of saying supply equals demand price and quantity supplied are inversely related price and quantity demanded are directly related price and quanti a) Supply curves are upward-sloping because price and quantity supplied are inversely related b) Supply curves are upward-sloping because price and quantity demanded are directly related c) Supply curves are upward-sloping because price and quantity supplied are directly related d) Supply curves are upward-sloping because supply equals demand price and quantity supplied are inversely related (