C# Version, String Interpolation ($) not working

Hi everyone, I would like to please know what version the C# script component is using, because I’m trying to do some string interpolation, and it says " Error (CS1056): Unexpected character ‘$’ (line 58) ", Thank you so much for your time.

The code is simply :

string str1 = ''first"
string str2 = “second”
string str = $"{str1} {str2}"

CodeDom, which is very old

I think C#4? That syntax has been there since after C#6. you can use string.Format though.