He believed it was Quetzalcoatl. Montezuma II was an Aztec leader that had a religious background. The reports of the Spanish landing confused him and he thought it was the return of their serpent God, Quetzalcoatl.
As the others have said, it's D.
And i'm not saying this to get the best answer, but I think you look really pretty lol =D from what i can see of the picture at least!
D, I believe.