Option c) 0

In Z distribution the mean is always 0 because the maximum value is + infinity and the minimum value is always - infinity

so means = (+infinity + (-infinity))/2

=(+infinity -infinity)/2

=0/2

=0

In Z distribution the mean is always 0 because the maximum value is + infinity and the minimum value is always - infinity

so means = (+infinity + (-infinity))/2

=(+infinity -infinity)/2

=0/2

=0