Suppose there are three relations as given below:

(x) R(a,b)= (0,1),(4,5),(8,9).

(y) S(b,c )=(1,2),(5,2),(5,6),(5,10),(13,10).

(z) T( c,d)=(2,3),(6,7)(10,11),(10,3)

the number of tuples in (R * S) * T, where * is the full natural outer join, is:

(a) 5

(b) 8

(c) 13

(d) 60