Final answer:
The given expression, x (x - 5)(2x + 1), represents a cubic polynomial. The highest power of x is 3, which means it is a cubic polynomial.
Step-by-step explanation:
The given expression, x (x - 5)(2x + 1), represents a quadratic polynomial.
A quadratic polynomial is a polynomial of degree 2.
It can be written in the form ax^2 + bx + c, where a, b, and c are constants and a is not equal to 0.
In this case, the expression can be expanded and simplified to get x^3 - 4x^2 - 5x.
The highest power of x is 3, which means it is a cubic polynomial.
Therefore, the correct answer is C) Cubic.