Which of the following circle equations represents a circle whose center is at (0, 0)?
A.
x2 + y2 = 45
B.
(x − 3)2 + (y − 5)2 = 0
C.
(x + 3)2 + (y − 3)2 = 0
D.
x2 + (y − 1)2 = 1