Dulce de leche.
But I would have equally chosen Tres Leches cake had it been one of the options. It's YUMMY, melt in your mouth cake!
A Tres leches cake, or Pastel de Tres leches (Spanish, "Three milk cake"), is a sponge cake,—in some recipes, a butter cake—soaked in three kinds of milk: evaporated milk, condensed milk, and either whole milk or cream.