Which operation shows that polynomials are a closed system under subtraction?

Question

Responses

(2x2+6x+1)−(3x2+3x+9)=−x2+3x−8

(2x2+6x+1)−(3x2+3x+9)=2x2+6x+1−3x2−3x−9

(2x2+6x+1)−(3x2+3x+9)=(2x2+6x−4)−(3x2+3x+4)

(2x2+6x+1)−(3x2+3x+9)=5x2+9x+10

Answer 1

The correct response is: (2x2+6x+1)−(3x2+3x+9)=−x2+3x−8