Answer: 504
Step-by-step explanation:
When we select r things from n things in a order , we use permutations.
Formula for permutation:
Given : The number of family members who are potential kidney donors. = 9
Number of people needed to be selected for best match, a second-best match, and a third-best match ( in an order)=3
Then, the number of possible orders are =
Hence, the number of possible orders 504.