Olórin was Gandalf’s original name before he became an Istar in J.R.R. Tolkien’s Middle-earth history.
Olórin is a Maia, a spiritual being who lives in Valinor. He is associated with wisdom and compassion, and Tolkien’s texts describe him as a pupil of Nienna. When the Valar send the Istari to Middle-earth to oppose Sauron, Olórin travels there in the form of an old man and becomes known as Gandalf.
The Istari are emissaries rather than ordinary human wizards. Their task is to encourage the peoples of Middle-earth to resist Sauron, not to defeat him through domination. Gandalf’s humility and concern for free peoples distinguish him from Saruman, who eventually seeks power for himself.
The other names in the choices refer to different identities. Curunír is Saruman’s Quenya name, Aiwendil is Radagast’s, and Mithrandir is one of Gandalf’s names in Sindarin. Thus Olórin identifies Gandalf before his mission in Middle-earth.