Final answer:
The domain of the relation R = (a, b), (c, d), (e, f) is a, c, and e.
Step-by-step explanation:
The domain of a relation is the set of all possible input values of the relation. In the given relation R = (a, b), (c, d), (e, f), the first elements of each ordered pair represent the input values.
So, the domain of R is the set of all the values of a, c, and e. Therefore, the correct answer is option (a) a, c, e.