A function is defined as a set of ordered pairs no two of which have the same first values or first component.
This means if more than one ordered pairs will have the same first component, the relation will not be a function.
In the given relation, the first component of 2nd and 3rd ordered pair is the same, so the relation {(2, 3), (4, 5), (4, 3), (3, 4)} is not a function.
So the Answer is False.