Answer: OPTION A
Explanation:
The formula that is used to calculate the surface area of a cone is:
![SA=\pi rl+\pi r^2](https://img.qammunity.org/2020/formulas/mathematics/high-school/gv6jdlms7mjbgdwv2x8y9po1ozx626g2w1.png)
Where "r" is the radius and "l" is the slant height.
You can identify in the figure that:
![l=12units\\r=3units](https://img.qammunity.org/2020/formulas/mathematics/high-school/73bn6m2llckouq68bxis40d2pk9cp7j02f.png)
Then, you need to substitute these values into the formula
.
Therefore, the surface area of this right cone is:
![SA=\pi (3units)(12units)+\pi (3units)^2](https://img.qammunity.org/2020/formulas/mathematics/high-school/9f37s5jouskwz3tjwq5ko4147b0pbkk9sx.png)
![SA=45\pi\ units^2](https://img.qammunity.org/2020/formulas/mathematics/high-school/sbjvaeonzfvr35ohhhoxz03focq22ysbuo.png)