Final answer:
The relation that is a partial order on the set {1, 2, 3, 4} is the reflexive relation.
Step-by-step explanation:
In this question, we need to determine which relation on the set {1, 2, 3, 4} is a partial order. A partial order relation must satisfy three conditions: reflexivity, antisymmetry, and transitivity. Let's consider each option:
- The reflexive relation is a relation where every element is related to itself. In this case, the relation {(1, 1), (2, 2), (3, 3), (4, 4)} is reflexive, satisfying the first condition.
- The symmetric relation is a relation where if (a, b) is in the relation, then (b, a) must also be in the relation. None of the options satisfy this condition.
- The transitive relation is a relation where if (a, b) and (b, c) are in the relation, then (a, c) must also be in the relation. None of the options satisfy this condition.
- The antisymmetric relation is a relation where if (a, b) and (b, a) are in the relation, then a must equal b. None of the options satisfy this condition.
Therefore, the only relation that satisfies all three conditions of reflexivity, transitivity, and antisymmetry is the reflexive relation.