The correct option is A [0,(1+m1m2)g,g]
Initial tension in spring
Fs=m1g
When the string is cut, spring tension does not change instantly. So, acceleration of m1 will be zero.
For block m2,
m2g+Fs=m2a
a=m2g+m1gm2=(1+m1m2)g
After string is cut, m3 is in free fall. So, its acceleration will be g.