The correct option is A x+y=3
Line of shortest distance is normal for both parabola and circle
Centre of circle is (2, 1)
Equation of normal to circle is y−1=m(x−2)⇒y=mx+(1−2m) (1)
Equation of normal for a parabola is y=mx−2am−am3 (3)
Comparing (1) and (2)
am3=−1⇒m3=−1⇒m=−1 (a=1)
Equation is y−1=x+2⇒x+y=3