Final answer:
The quadratic expression written in standard form is -x^2 - 5x + 7.
Step-by-step explanation:
The quadratic expression that is written in standard form is C. -x^2 - 5x + 7.
In standard form, a quadratic expression is written as ax^2 + bx + c, where a, b, and c are constants.
In this case, the expression -x^2 - 5x + 7 has the leading coefficient a as -1, the linear coefficient b as -5, and the constant term c as 7, so it is written in standard form.