Comedian Bill Cosby, in an interview that aired on Saturday, declined to answer questions by a National Public Radio journalist about accusations of sexual assault that resurfaced in recent weeks. Cosby, 77, responded by shaking his head to signal “No” at least twice when NPR’s Scott Simon asked him to respond to the sexual assault accusations, including those made by former aspiring actress Barbara Bowman in an op-ed in the Washington Post earlier in the week.