Which of the following is the correct notation for the complex number

To solve the problem shown in the figure attached, you must apply the proccedure shown below:

 1. You have the following complex number given in the exercise:

 √(-36)+10

 2. By definition, you have that:

 i=√(-1)

 3. Then:

 √(36)=6
 √(-36)=6√(-1)=6i

 3. Therefore, you have the correct notation for the complex number √(-36)+10 is:

 10+6i

 The answer is the option A: 

 A. 10+6i