Final answer:
Option C, 2x(4y² + 5y), is factored completely as it is expressed as a product of two factors and cannot be factored further.
Step-by-step explanation:
The question asks which polynomial is factored completely. The factored completely polynomial is option C, 2x(4y² + 5y). This polynomial is factored completely because it is expressed as a product of two factors, 2x and (4y² + 5y), and cannot be factored further. Options A, B, and D are not polynomials, and so cannot be factored, while E is a quadratic polynomial that can potentially be factored further.