Consider the schema R(A, B) foreign key (B) references to S
S(A, B) foreign key (A) references to R
(None of the attributes are nullable)
Which of the following is guaranteed to produce fewer than, or at most the same, number of tuples as any of the others?
a. πA(R) ⋈ πB(S).b. R ⋈ πB(S).c. R ⋈ S. d. πA(R) ⋈ S. e. None of the above.