Answer:
A. 
B. 
C. 
Step-by-Step Explanation:
A. Tangent to x-axis, r=4, contains (-5,8)
The equation of a circle is this: 
Therefore, we know that our equation will be: 
Because the circle is tangent to the x-axis, the point (-5,8) will be the top of the circle.
Therefore, the center is (-5,4), where -5=h and 4=k.
The answer is 
B. Diameter endpoints (2,5) and (0,3)
To solve for the diameter, we can use this equation: 

Because the radius is half of the diameter, 
Therefore, we know that our equation will be: 
Then, we can decipher that h=1, as the midpoint of 0 and 2 is 1, and k=4, as the midpoint of 3 and 5 is 4.
The answer is 
C. Center on x=3, tangent to y-axis at (0,5)
We can see that the center is (3,5). Therefore, the equation is 
To solve for r, we can substitute the point (0,5) into the equation.

The answer is 
<em>Hope this helped!</em>