Final answer:
If R is selected fifth, we cannot determine which of the options (a), (b), (c), or (d) must be true.
Step-by-step explanation:
If R is selected fifth, it means that there are four names selected before R. Since the question does not specify the order of the other options, we cannot determine which one must be true. Therefore, none of the options (a), (b), (c), or (d) can be determined to be true.