What is the last name of the person Frank proposes to?  Answer the above question based on the context below:  In turn-of-the-century Oakland, California, the teenaged Myrtle McKinley is expected to follow high school by attending a San Francisco business college. Instead, she takes a job performing with a traveling vaudeville troupe, where she meets and falls in love with singer-dancer Frank Burt. Frank proposes they marry and also entertain on stage together as an act, which proves very popular. Myrtle retires from show business after giving birth to daughters Iris and Mikie, while her husband goes on tour with another partner. A few years later, less successful now, Frank persuades his wife to return to the stage. The girls are cared for by their grandmother as their parents leave town for months at a time. Iris and Mikie are school girls when they are given a trip to Boston to see their parents. Iris meets a well-to-do young man, Bob Clarkman, and is permitted to attend an exclusive boarding school there. She is embarrassed by her parents' profession, however, and mortified at what the reaction will be from Bob and all of her new school friends when they learn that her parents are performing nearby. Myrtle and Frank take matters into their own hands, arranging with the school to have all of the students attend a show. To her great relief, Iris is delighted when her classmates adore her parents' sophisticated act. By the time she's out of school and ready to marry, Iris wants to go into show business herself.
A:
McKinley