Find the equation of the circle with center at
(-2,1)
and passes through the point
(3,1)
.

Radius (R) is equal to the distance between the points (-2,1) and (3,1)
R² = (-2 - 3)² + (1 - 1)² = (-5)² + 0 = 25
R = 5 

Equation of the circle:
(х-(-2))² + (у-1)² = 5²
(х+2)² + (у-1)² = 25

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.