って vs が. JLPT 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?




「って」 is the only correct answer here.

When someone asks the question 「ねえ, 田中さん（ ）どんなひと？」, the asker should basically
have no knowledge of Tanaka, correct?

That is where the **topic-introducing 「って」** comes into place --- "this Tanaka
guy", "this guy called --- what was his name, Tanaka?", etc.

Using 「が」 is very unnatural (I would call it plain wrong, actually) when
asking about something/someone you know little to nothing about. You say 「これ
**は** なんですか。」 and never 「これ **が** なんですか。」.

Regarding 「は」, which is not among the choices given, it is "possible" to use
it. BUT it requires a certain condition under which the question
「ねえ、田中さんはどんな人？」 is asked. The condition is that the asker has already asked
about at least one other person before asking about Tanaka. If Tanaka is the
only (or first) person you are asking about, the only correct choice is to use
「って」.

