What structural decision does a translator make when translating an original text?

a. Character development

b. Word choice

c. Conflict resolution

d. Dialogue

Actually, I am not too sure the question is well phrased. Translators do not decide on character development, conflict resolution or dialogue: they just need to stay faithful to the original text, those decisions are up to the original author.

so the best answer is "word choice", but that's not exactly "structural".

Unless the option of "dialogue" means the word choice in dialogue, but I don't think so.

I would say that a good answer would be "word order" or "grammatical construction".