GATE CS 2015 Set 2 — Question 42

Consider two relations \(R_1(A, B)\) with the tuples \((1, 5), (3, 7)\) and \(R_2(A, C) = (1, 7), (4, 9)\). Assume that \(R(A, B, C)\) is the full natural outer join of \(R_1\) and \(R_2\). Consider the following tuples of the form \((A, B, C)\):

\(a = (1, 5, \text{null})\), \(b = (1, \text{null}, 7)\), \(c = (3, \text{null}, 9)\), \(d = (4, 7, \text{null})\), \(e = (1, 5, 7)\), \(f = (3, 7, \text{null})\), \(g = (4, \text{null}, 9)\)

Which one of the following statements is correct?