Answer:
Function is decreasing on (-8,infinity)
Step-by-step explanation:
The given function is 
The first derivative is given by

For the function to be decreasing, we have

Divide both sides by -2. Since, we are dividing by a negative number hence, the inequality sign will change.

Subtract 8 to both sides

Therefore, the function is decreasing on (-8,infinity)
First option is correct.