Answer:
b. B, A, C
Explanation:
To solve this problem, let us find the net forces they are experiencing.
 Net force  = mass x acceleration
Object A;  mass  = 8kg and acceleration  = 4m/s²
         Net force  = 8 x 4  = 32N
Object B;  mass  = 10kg and acceleration  = 3m/s²
         Net force  = 10 x 3  = 30N
Object C:  mass  = 7kg  and acceleration  = 5m/s²
          Net force  = 7 x 5 = 35N
So, increasing order of their net force;
       B < A < C