Answer:
Option B
Explanation:
Given the equation of a circle is x2+y2−4x+6y−12=0, whose centre is (2,-3) and radius
=√22+(−3)2+12=√4+9+12=5
Now , according to given information , we have the following figure
x2+y2−4x+6y−12=0
Clarly, AO⊥BC, as O is mid-point of the chord

Now, in ΔAOB , we have
OA=√(−3−2)2+(2+3)2
=√25+25=√50=5√2
and OB=5
∴AB=√OA2+OB2
√50+25=√75
= 5√3