User

When the zero conditional mean holds, which of the following is wrong:

a$.$ E$($ui$)=0$

b$.$ E$($ui$|$x$)=0$

c$.$ E$($ui$|$xi $=9)=0$

d$.$ E$($ui$|$xi $=9)=0$ and E$($ui$|$xi $=11)=0$