Which describes all of the values for which the graph is positive and decreasing?
a. all real values of x where x < −1
b. all real values of x where x < 1
c. all real values of x where 1 < x < 3
d. all real values of x where x > 3

The statement that describes all of the values for which the graph is positive and decreasing is:

C.) ALL REAL VALUES OF X WHERE 1 < X < 3

The number 1 ensures that the value of x will remain positive.
Since x is less than 3, then the value of x is decreasing.