I need help with this problem. With the remote learning I am having a hard time understanding the problem. Thank you.

Neptune is working on a research paper but its only local planetary library has made it so that each member can only take out a single book. In front of Neptune is an aisle of n different books relevant to its paper, where n is a positive integer. Neptune doesn't have enough time to go through every book, so it wants to select a book uniformly at random. In other words, Neptune looks to find a scheme that will guarantee that it selects the ith book with probability 1, where 1