Detailed Instructions: In this task, you're given a question, along with a context passage. The passage will not have a direct answer to the question, but can include some information and a clue for the answer. Assuming you can only obtain information about one entity in the passage, your job is to determine whether information from the passage can be used to answer the question. Indicate your choice as `a` for Yes or `b` for No.
Q: Question: What book first introduces the white wizard? Passage:Meanwhile, the wizard Gandalf the White and the hobbit Pippin arrive at Minas Tirith to warn Denethor, the Steward of the Throne, about the upcoming war—only to discover that the Steward has become insane and means to take his own life. Frodo and Samwise continue toward Mount Doom (eluding Ringwraiths and infiltrating a "battalion of orcs" in the process) only to be attacked by Gollum. As Sam holds Gollum off, Frodo reaches the Crack of Doom; but is subverted by the Ring. At the same time, Gondor's neighboring country, Rohan, helps it claim victory in the Battle of Pelennor Fields, where King Théoden and the Witch-King of Angmar are slain. Upon his own arrival, Aragorn plans to confront Sauron at the gates of Mordor. Here, he quarrels with the Mouth of Sauron and the two armies prepare for battle.

A:
b