とする versus なら (and other confusion)

Question

I have a question about conditionals and assumptions. Please consider the following simple situation:

Person A: You're very good at Japanese.

Person B: If that is so, it's all thanks to my teacher.

I would like to know the most natural way (or ways) to say "If that is so." I considered several combinations. Could someone please address each or some of them and explain if any are acceptable or unacceptable. If none of these are appropriate, could someone please provide a better alternative? I included my reasoning to demonstrate that I thought about the topic. Feel free to point out flaws in it or even ignore it completely if it's easier.

1. そうなら(or だったら) 先生のおかげですから。
   I thought なら might work since なら can be used to create a conditional with a "given this circumstance" implication. "Given that it is so..." I think this slightly changes the meaning but perhaps it is appropriate nevertheless.
   
   

2. そうだとしたら...。
   This was my original idea before I started questioning myself. I reasoned that "If it is so..." is actually an assumption, so a とする expression would be appropriate. But then I hesitated because nothing I could find on とする suggested it could be used this way. It seems to me, in the most abstract sense, とする restricts the universe of conversation and what follows is an implication of that restriction. Consequently, I'm not sure "it's all thanks to..." would work with this pattern since it is not an implication. Please ignore the previous 2 sentences if they don't make sense and are hindering an answer...
   
   

3. そうだとすれば...。
   I do not expect this to be correct but it's more of an instinct I have on the use of えば when referring to things in the past rather than understanding so I'd appreciate an explanation if it's easy.
   
   

4. そうだとすると...。
   I understand the と creates a definite conditional in the sense that, "if A happens, B will happen also as a matter of course." So I strongly suspect that this is not proper.

5. そういうなら...。
   I think this would create an expression along the lines of "Given that it is as you say..." which I guess might be more appropriate since Person A is in claiming something.

6. そういうとしたら...。
   Combination of 2 and 5.

Answer 1

Among them, 3.そうだとすれば is the most natural and automatically 2.そうだとしたら is the most natural too. 1.そうなら or そうだったら are good. 4.そうだとすると is ok.

Edit: If you choose between 2 and 3, 2.そうだとしたら is more colloquial and can express the nuance of "chances are".

5.そういうなら and 6.そういうとしたら mean "if you say so", not "if it's as you say", which would be （もし、あなたの）言うとおりなら.