Randomly Select based on a Multi-select Question which is Nested in a Roster

Dear Survey Solution Team,

Under the Parcel roster, a List question is “List the names of the fish ponds”. Then, a Multi-select question is based on the List question: "Which of the fish ponds are currently in stock?". My goal is to do a random selection of the fish ponds based on the answers to this Multi-select question. Please help. Thanks much!

Best,
Percy

Please note that the multi-select question is nested in the parcel roster.