Robert Caro is the two-time Pulitzer Prize-winning author of “The Power Broker” and “The Years of Lyndon Johnson.” Host Robin Young talks to him about “Working,” his latest book. Also, Vanessa O’Brien has climbed the tallest mountains on the earth and she’s just gone into the deepest place on the planet: the Challenger Deep in the Pacific Ocean’s Mariana Trench. Jeremy Hobson speaks with her.