The correct option is D 2m1m2m1+m2
Since the masses are unequal ( m1>m2), the whole system will
attain a constant acceleration 'a' (say). At that moment, we calculate
the reading of the spring. Since the spring and the pulleys are assumed
massless, the tension in the whole system is same.
Writing , force equations for each body individually ,
m1g−T=m1a
T−m2g=m2a
Simplifying , we have T=2m1m2gm1+m2
The spring balance measures the reading by tension and hence , Reading is 2m1m2m1+m2