Answer:
An equation of the circle with centre (5,7) and radius 2 is 

Option A is correct.
Explanation:
A circle in the xy-plane has centre (5,7) and radius 2. Which of the following is an equation of the circle.
The equation of circle is of form: 
 where (h,k) is centre and r is radius.
 where (h,k) is centre and r is radius.
We have centre (5,7) so, we have h = 5 and k = 7
We have radius = 2 so, r = 2
Putting values in the equation and finding the required equation:

So, an equation of the circle with centre (5,7) and radius 2 is 

Option A is correct.