Mozart intended this aria to be relatively simple, as the role of Papageno was played by a fairly inexperienced singer. He achieved this by

Question

doubling the vocal line in the violins.
writing in strophic form, in which the words are set to repeating melodic verses.
stating the melody in its entirety in the orchestral introduction before the singer begins to sing.
all of the above

Answer 1

all of the above