answers: Shaunae Miller
context: Athletics at the 2012 Summer Olympics – Women's 4 × 400 metres relay ] The Women's 4 × 400 metres relay competition at the 2012 Summer Olympics in London, United Kingdom was held at the Olympic Stadium on 10–11 August. In the final, the USA had individual 400m bronze medalist DeeDee Trotter lead off. From the gun she put distance on the rest of the field. While the display clock read 49.57 for her split, it was more like 50.3, handing the baton to Allyson Felix several meters ahead. With the miscalculation Felix ran close to a 48.1 split, reported </s> Deon Hemmings is the most successful woman, with her 1996 gold and 2000 silver medals, and is the only female athlete to win multiple medals. It is relatively common for 400 m hurdles athletes to also be part of their nation's team for the 4×400 metres relay at the Olympics. The United States is by far the most successful nation in the men's event with 18 gold medals and 40 medals overall—more than half the medals available. American men have swept the medals on five occasions. The American women have the highest medal total, with seven, but an American woman </s> 2017 World Championships in Athletics – Women's 400 metres The women's 400 metres at the 2017 World Championships in Athletics was held at the London Olympic Stadium on and 9 August. In wet conditions, Shaunae Miller-Uibo took an early lead, which she maintained coming onto the home stretch, with Allyson Felix in second and Phyllis Francis and Salwa Eid Naser gaining on both of them. Miller-Uibo stumbled and slowed to a jog, being passed by Francis, Felix, and Nasser. Francis continued on to win while Nasser, breaking her own national record, dipped past Felix on the line. Before the competition
question: who won the women 's 400 meter dash in the olympics