The market demand for labor curve is correctly described by which of the following?
a) It is the horizontal summation of all the individual firm demand for labor curves.
b) It is steeper than the horizontal summation of all the individual firm demand for labor curves.
c) It is one of the individual firm demand curves multiplied by the number of firms in the industry.
d) It is flatter than the horizontal summation of all the individual firm demand for labor curves.
e) It is the vertical summation of all the individual firm demand for labor curves.