In the model E(y) = + 1x + 2z, where z = 1 for females and

In the model E(y) = α + β1x + β2z, where z = 1 for females and z = 0 formales,

(a) The categorical factor has two categories.

(b) One line has slope β1 and the other has slope β2.

(c) β2 is the difference between the mean of y for females and males.

(d) β2 is the difference between the mean of y for females for males, controlling for x.