[Grammar] Conditionals

[barnej0096]

I have a question about conditionals, I found an example:
Did California become an important area because they found gold there?
Would.....?
The answer is: Would California have become an important area if they haven't found gold there?
And I don't understand why I should use: "if they haven't found gold there". Is it incorrect to say: "Would California have become an important area if they hadn't found gold there?"=3rd conditional?

 

[5jj]

Welcome to the forum, barnej. :hi:

The answer given is incorrect. Your answer, with 'hadn't' is correct

 

[barnej0096]

Okey, thanks for help :-D