Instructions Full Game: These are multiple-choice quizzes with four possible answer choices that include all questions in a given set.     
With twenty in total, what American pair has the most Grand Slam women's doubles titles since 1950?
Serena Williams & Venus Williams
Doris Hart & Shriley Fry Irvin
Rosemary Casals & Billie Jean King
Martina Navratilova & Pam Shriver