"Selection" in the context of Eliezer's experience in the concentration camp refers to the process by which Nazi officers determined which prisoners were fit to work and which would be sent to their deaths. It is ironic for Eliezer to call selection a "present" because, while a present typically signifies a gift or something positive, in this instance, it is a morbid and cruel evaluation of one's ability to endure further suffering or face imminent death.
