Final answer:
The hymn "A Mighty Fortress is our God" was written by Martin Luther, not by any of the composers listed. Johann Sebastian Bach later arranged the hymn, but he did not write the original.
Step-by-step explanation:
The hymn "A Mighty Fortress is our God", or "Ein Feste Burg ist Unser Gott" in the original German, was written by Martin Luther in the 16th century. This hymn is a classic piece of Protestant Reformation history and remains a staple in many Christian denominations today.
Although Johann Sebastian Bach wrote a famous arrangement of this hymn, he is not the original author. Instead, Martin Luther is credited with both the lyrics and the original composition of the melody. Bach's arrangement demonstrates his ornate and complex harmonic understanding, which enriched Luther's initial work. Nevertheless, Bach's contribution is a separate aspect from the original creation of the hymn.
None of the composers listed in the multiple-choice options (Johann Sebastian Bach, Ludwig van Beethoven, Wolfgang Amadeus Mozart, Franz Schubert) actually wrote the hymn. They all are notable composers who have significantly contributed to classical music, often utilized in various films to convey deep emotions, as Stanley Kubrick did with the works of Strauss and Beethoven in his films.