The correct option is
A x+2y−3=0Equation of the circle is
x2+y2+2x−4y−11=0.We know that the standard equation of the circle is x2+y2+2gx+2fy+c=0.
Comparing the given equation with the standard equation, we get g=1,f=−2 and c=−11
We also know that coordinates of the centre of the circle (−g,−f)=(−1,2).
Since the diameter perpendicularly bisects the chords intercepted on 2x−y+3=0,
Therefore the equation of the diameter is x+2y+k=0.
We also know that the diameter passes through the centre (−g.−f)
Therefore, (−1)+2×2+k=0⇒k=−3.
Thus, the equation of the diameter is x+2y−3=0.