Relation Types

- Reflexive
- Symmetric
- Transitive
- Surjective

Explanation

A relation is a set of ordered pairs that relate elements from two sets. The four types of relations are reflexive, symmetric, transitive, and surjective.

Reflexive Relation: A relation is reflexive if every element of the set is related to itself. For example, the relation "is equal to" is reflexive because every element is equal to itself.

Symmetric Relation: A relation is symmetric if whenever (a,b) is in the relation, then (b,a) is also in the relation. For example, the relation "is a sibling of" is symmetric because if A is a sibling of B, then B is also a sibling of A.

Transitive Relation: A relation is transitive if whenever (a,b) and (b,c) are in the relation, then (a,c) is also in the relation. For example, the relation "is an ancestor of" is transitive because if A is an ancestor of B and B is an ancestor of C, then A is also an ancestor of C.

Surjective Relation: A relation is surjective if every element in the second set is related to at least one element in the first set. For example, the function f(x) = x^2 is surjective because every non-negative number has a square root.

Answer

Therefore, the correct answer is option 'B' (Surjective) because it is not a type of relation. It is a property of functions.