We, as readers, cannot be absolutely certain why the Elders choose Jonas to be the next Receiver of Memory. Jonas is portrayed as an intelligent, honest, and introspective young man who takes his studies and obligations seriously. The Elders, who observe every child carefully in order to ensure the accuracy of each Assignment, must have seen that; in fact, they realize that he is mature beyond his years. There must have been other responsible eleven-year-olds in the community, but we are told that none have come close to becoming a Receiver for a number of years. The main characteristic that distinguishes Jonas from the rest of the members of the community is his "capacity to see beyond." It is not quite clear how the Elders know that Jonas has this capacity; they are likely relying on the Giver's recommendation. Originally, Jonas is perplexed when he hears the reason for him being selected, but he slowly recalls incidents when he was able to see things differently than everyone else. While the world everyone else in black and white, Jonas is able to see that an apple is red and his friend Fiona's hair is red.
Ironically, the qualities for which Jonas is selected—his wisdom, integrity, and sense of responsibility—are the reasons for him being unable to live with the knowledge of the things done in the community for the sake of maintaining "peace." These include the Release (i.e. murder) of babies who fail to thrive, the elderly, and anyone who does not follow the rules. Jonas chooses to save Gabriel from Release and leaves the community, thus defeating the whole purpose of him becoming the Receiver.