Determine Where the Graph of the Function $f(x)=9 x-\sqrt{4-x^{2}}$ Is Concave Upward and Where It Is Concave Downward

Multiple Choice

Determine where the graph of the function $f(x) =9 x-\sqrt{4-x^{2}}$ is concave upward and where it is concave downward. Also, find all inflection points of the function.

A) CU on $(-2,2)$ ,
IP none
B) CU on $(-\infty,-2)$ and $(2, \infty)$ , CD on $(-2,2)$ ,
IP $(-2,-18)$ and $(2,18)$
C) CD on $(-2,2)$ ,
IP none
D) CU on $(-2,2)$ , CD on $(-\infty,-2)$ and $(2, \infty)$ ,
IP $(-2,-18)$ and $(2,18)$