Decreasing function
We want to analyze when the function is decreasing,this means, where "it goes down"
We can see that it is at its highest point at x = 2.5
then it stops at x = 5.5
Then it decreases an instant after 2.5 until an instant before 5.5. Then it is deacreasing at
2.5 < x < 5.5
Answer: A
