A circle of radius rrr is dropped into the curve y=x2y=x^2y=x2 such that it only touches the curve. The circle's centre is (0,c)(0,c)(0,c). Express ccc in terms of rrr. A1+2r22\frac{1+2r^2}{2}21+2r2B1−4r24\frac{1-4r^2}{4}41−4r2C4rr2−2\frac{4r}{r^2-2}r2−24rDr24−1\frac{r^2}{4}-14r2−1E1+4r24\frac{1+4r^2}{4}41+4r2F1−6r22\frac{1-6r^2}{2}21−6r2Gr3−r4\frac{r^3-r}{4}4r3−r