A normal statement would "Han eller hon svarar", but in a question the verb comes first:
"Svarar han eller hon?".
If you have two verbs, e.g. "har svarat" (have answered) or "ska svara" (will answer), the modal verb and the main verb are split like this:
"Har han eller hon svarat?"
"Ska han eller hon svara?"
When learning a language, you learn better if you stop judging it based on the logic of your own native language. You also learn better if you do not question the meaningfulness or usefulness of sentences you are asked to learn, thess are just grease for the dry grammar cogs.
Both in Swedish and in English, it is possible to form questions either like you did, by just adding a question mark and changing intonation, or by changing word order (and maybe add do in the process in English). Since this works pretty much the same in both languages, we only accept the same type of translation. So questions formed by just adding a question mark are only accepted translations if the Swedish question is already formulated that way.