って vs が. JLPT question?

Question

I'm looking through JLPT N3 questions and have come across this one: > A: ねえ　（　　　）　どんなひと？ > B: とても親切でいい人だよ The possible answers are: 1. 田中さんが 2. 田中さんで 3. 田中さんって 4. 田中さんでも Number 4 makes no sense at all. "Tanaka-san but"? Number 2 is a bit weird. We're not doing anything with Tanaka. It is wrong. However, my instinct was that number 1 was correct. It is not. 3 is. I understand the use of って。 Its saying on the subject of whatever->this. But が also seems that it would work fine. Tanaka is the object we're talking about. Why is 1 so wrong and 3 has to be right? Also, would は be strictly okay in this sentence?

Answer 1

You're not wrong in thinking this is pretty confusing, it really is kind of a weird setup.

I don't know the specific rule, but if you read it out loud, it sounds like if you use the correct answer, its part of a casual conversation.

が is not used to mark a subject, it is an identifier, see this https://www.wasabi-jpn.com/japanese-grammar/ha-vs-ga-five-points-you-need-to-know/ and that might help you :)

は could also be used instead, however, if you hear it as part of a casual conversation, you might recognize why the って is used.