G1: Regular Grammar and G2:Regular Grammar
Suppose L1= L(G1) and L2 = L(G2)
Take another language L such that
L= (L1 - L2) U(L2 - L1) //EXOR of Both
L= (L1∩ L2c) U (L2∩L1c)
L1 and L2 are regular languages hence closed under complement and intersection
L=Regular U Regular = Regular
And Regular is closed under emptiness property, so if L is empty language it means both have disjoint property, so overall problem is Decidable which makes option (A) true.