Iran presented its long-awaited answer to a package of Western nuclear incentives Tuesday, saying that it will negotiate on its nuclear program but failing to indicate that it will halt uranium enrichment. Margaret Warner reports on Iran's response. Betty Ann Bowser reports on the state of welfare, ten years after a landmark reform bill was signed into law. The guests this episode are Aaron Friedberg, Trita Parsi, Ron Haskins, Sharon Parrott, Priscilla Labovitz. Byline: Gwen Ifill, Margaret Warner, Betty Ann Bowser, Jeffrey Brown, Ray Suarez