Principles of economic, What effect should each of the following have on the demand for gasoline

What effect should each of the following have on the demand for gasoline in a competitive market?  State what happens to demand.  Explain your reasoning in each case and relate it to a demand determinant.

a.       an increase in the number of cars

b.      the economy moves into a recession

c.       an increase in the price of car insurance, taxes, maintenance

d.      consumer expectations of substantial price increases in gasoline