“grey’s anatomy” (9 p.m., abc): “Grey’s Anatomy” offers an

“grey’s anatomy” (9 p.m., abc): “Grey’s Anatomy” offers an intriguing “what if” twist with an episode that envisions alternate fates for the show’s characters. Meredith (Ellen Pompeo), for example, imagines what life would have been like if her late mother (Kate Burton) had not fallen victim to Alzheimer’s.

tv listings, B6