When our neighbor was cheated by a scam artist, we all asked, “How could anyone be so ____?”

Select the word with the most appropriate connotations to fill in the blank and fit the tone of the sentence.

I cant decide on Gullible OR trusting.

they both make sense T.T ,I'm thinking along the lines of gullible, but trusting , I heard ppl used it before. Like more is it like How can anyone be so stupid, then I'm leaning towards gullible, but ..