In how many ways can 8 people be seated in a row if

a) there are no restrictions on the seating arrangement?

b) persons A and B must sit next to each other?

c) there are 4 men and 4 women and no 2 men or 2 women can sit next to each other? d) there are 5 men and they must sit next to each other?

e) there are 4 married couples and each couple must sit together?