Can I get some help

Given:
The expression is
[tex]2x^4+2x^3-x^2-x[/tex]
The steps are given.
To find:
The mistake in her steps.
Solution:
We have,
[tex]2x^4+2x^3-x^2-x[/tex]
The correct steps are shown below.
Step 1: Taking out x as common factor.
[tex]=x(2x^3+2x^2-x-1)[/tex]
Step 2: Now, taking out 2x² as common factor from first two terms (first group of terms) and -1 form last two terms (second group of terms) in the parentheses.
[tex]=x(2x^2(x+1)-1(x+1))[/tex]
Step 3: Taking out (x+1) as common factor.
[tex]=x(2x^2-1)(x+1)[/tex]
She incorrectly factored -1 from the second group of terms.
Therefore, the correct option is B.