Sets, Relations and Functions

Let N be the set of natural numbers and a relation R on N be defined by R = (x,y) ∈ N × N : x³ - 3x²y - xy² + 3y³ = 0. Then the relation R is: (1) symmetric but neither reflexive nor transitive (2) reflexive but neither symmetric nor transitive (3) reflexive and symmetric, but not transitive (4) an equivalence relation