Answer:
b. x² + y² = 12²
Explanation:
A circle has a general equation of:
(x + h)² + (y – k)² = r²
where h and k are the center (h,k) and r is the radius.
The circle is centered at origin (0, 0), so h=0, k=0.
The diameter is 24, but we want the radius instead. So divide the diameter by 2 to get the radius. r = 24/2 = 12
Plug it into the equation
(x + h)² + (y – k)² = r²
(x + 0)² + (y – 0)² = 12²
x² + y² = 12²