Answer:
Option C.
Step-by-step explanation:
If the graph of a function f(x) lies above the x-axis, then f(x) > 0.
If the graph of a function f(x) lies below the x-axis, then f(x) < 0.
From the given graph it is clear that the graph of f(x) intersect the x-axis at x=3.
Before x=3 the graph lies below the x-axis. So,
[tex]f(x) < 0[/tex] over the interval [tex](-\infty,3)[/tex].
After x=3 the graph lies above the x-axis. So,
[tex]f(x) > 0[/tex] over the interval [tex](3,\infty)[/tex].
Therefore, the correct option is C.