If a binary relation is defines as r = {(4,5), (5,4), (5,4), (5,6),(6,4)}, then domain of R is ?

{4,6}

{4,5,6}

{4,5}

None of these

The domain of a relation is the set of all first elements in the ordered pairs. For the relation R:

The first elements are

4, 5, and 6

So, the domain of 𝑅 is {4,5,6}.