若圆C与圆(x+2) 2 +(y-1) 2 =1关于原点对称,则圆C的方程是( ). A.(x-2) 2 +(y+1) 2 =1 B.(x-2) 2 +(y-1) 2 =1 C.(x-1) 2 +(y+2) 2 =1 D.(x+1) 2 +(y-2) 2 =1