It is observed that two goods, M and N, are complements. To test that belief, an economist examines the data and determines that the cross-price elasticity of demand between them is 3.5. Based on this information:
a) M and N are substitutes.
b) The demand for M decreases when the price of N increases.
c) The demand for N decreases when the price of M increases.
d) M and N are independent goods.