Which of the following is included in the calculation of GDP?
A. The purchase of a new edition of a foreign textbook that was produced in a different nation.
B. The purchase of ink and paper supplies by a textbook company for the production of new textbooks.
C. The purchase of tutoring services from a tutor who holds citizenship outside the country but resides within the country.
D. The purchase of a used textbook from a friend who took the same class last year.