Let $A = \{1, 2, 3, 4, 5, 6, 7\}$. Then the relation $R = \{(x, y) \in A \times A : x + y = 7\}$ is\\
(1) symmetric but neither reflexive nor transitive\\
(2) an equivalence relation\\
(3) reflexive but neither symmetric nor transitive\\
(4) transitive but neither reflexive nor symmetric