Eight students (Anna, Brian, Carol, ...) are to be seated around a circular table with eight seats, and two seatings are considered the same arrangement if each student has the same student to their right in both seatings.

(a) How many seatings of the eight students are there?

(b) How many arrangements of the eight students are there?

(c) How many arrangements of the eight students are there with Anna sitting next to Brian?

(d) How many arrangements of the eight students are there with Brian sitting next to both Anna and Carol?

(e) How many arrangements of the eight students are there with Brian sitting next to either Anna or Carol?