IF Statement multiple conditions, same statement

Question

Hey all, looking to reduce the code on my c# if statements as there are several repeating factors and was wondering if a trimmer solution is possible.

I currently have 2

Answer 1

if (checkbox.checked && columnname != a && columnname != b && columnname != c)
    {
      "statement 1"
    }
else if (columnname != a && columnname != b && columnname != c 
        && columnname != A2)
    {
      "statement 1"
    }

is one way to simplify a little.