The relation R in the set A = {1, 2, 3} given by R = {(1, 2), (2, 1)} is :

Reflexive Symmetric Reflexive but not symmetric Equivalence Relation

Symmetric

A = {1, 2, 3}     R = {(1, 2), (2, 1)} for every (a, a) ∈ A (a, a) ∈ R → not true (NOT reflexive) for every (a, b) ∈ R (b, a) ∈ R (True ⇒ Symmetric) as (1, 2) ∈ R ⇒ (2, 1) ∈ R, true Option 2 → Symmetric