What Was The Cause of the Hindenburg Crash?

As we know from history, the Zeppelin "Hindenburg" exploded, crashed, and burned at Lakehurst, New Jersey, on May 6, 1937. Some claim that the hydrogen ignited as the result of static electricity, made worse by the poor weather conditions that evening (damp, raining, some lightning), while others contend that it was sabotage designed to protest the Nazi regime. Which do you think it was, and why? Thanks to all who respond.