The Graph of the Derivative $f^{\prime}(x)$ Of a Continuous Function F Is Shown

Multiple Choice

The graph of the derivative $f^{\prime}(x)$ of a continuous function f is shown. On what intervals is f decreasing? .

A) $(2,6)$
B) $(8,9)$
C) $(-1,1)$
D) $(4,6) \cup(7,9)$
E) None of these