Given R={(1,2),(2,3),(3,3)} on the set {1,2,3,4}, find the minimum number of elements to add so that R becomes an equivalence relation. An equivalence relation must be reflexive, symmetric, and transitive. Since (1,2) and (2,3) are \in R, by symmetry and transitivity, 1, 2, and 3 must all be \in the same equivalence class. Element 4 is \in its own class. So the equivalence classes are {1,2,3} and {4}. Reflexive: (1,1),(2,2),(3,3),(4,4) Symmetric pairs for class {1,2,3}: (1,2),(2,1),(1,3),(3,1),(2,3),(3,2) Total required pairs: (1,1),(2,2),(3,3),(4,4),(1,2),(2,1),(1,3),(3,1),(2,3),(3,2) = 10 pairs Already \in R: (1,2),(2,3),(3,3) = 3 pairs Need to add: (1,1),(2,2),(4,4),(2,1),(1,3),(3,1),(3,2) = 7 pairs The correct answer is Option 2 : 7.