Estimated demand for a given brand of soccer shoes (divas) is given by QD=1200-30P-30Pb+10Pc+2Pd+100A

Where QD = Quantity demanded in pairs of shoes. P= Price of a pair of Didas soccer shoes in Euros, Pb=Price of soccer ball in Euros, Pc=Average price of shoes sold by competitors in Euros, Pd=Price of a soccer jersey, A= advertising expenditure (in 100s of Euros)

How many of the following statements are correct?

- From the demand curve one can infer that if all prices stay the same then a higher level of advertising will lead to a Lower quantity demanded for Didas shoes

-From the demand curve, once can infer that Didas shoes and soccer jerseys are substitutes

-From the demand curve, one can infer that the competitors shoes and soccer balls are complements

a. only two of the statements are correct

b. Only one of the statement is correct

c. None of the statements is correct

d. All three are correct