Read this and answer the question. If the question is unanswerable, say "unanswerable".

The year 1789 brought the French Revolution and with it the first division of Alsace into the départements of Haut- and Bas-Rhin. Alsatians played an active role in the French Revolution. On 21 July 1789, after receiving news of the Storming of the Bastille in Paris, a crowd of people stormed the Strasbourg city hall, forcing the city administrators to flee and putting symbolically an end to the feudal system in Alsace. In 1792, Rouget de Lisle composed in Strasbourg the Revolutionary marching song "La Marseillaise" (as Marching song for the Army of the Rhine), which later became the anthem of France. "La Marseillaise" was played for the first time in April of that year in front of the mayor of Strasbourg Philippe-Frédéric de Dietrich. Some of the most famous generals of the French Revolution also came from Alsace, notably Kellermann, the victor of Valmy, Kléber, who led the armies of the French Republic in Vendée and Westermann, who also fought in the Vendée.

Which song was played for the first time in Strasbourg that would later become the French national anthem?
La Marseillaise