The spring balance A read 2 k.g. with block of mass m suspended from it. A balance B reads 5kg. when a beaker with liquid is put on the pan of the balance. The two balances are now so arranged that the hanging mass is inside the liquid in the beaker as shown in flg. In this situation.
When the block is immersed in the liquid, buoyant force B acts on it in upward direction. By Newton's third law, the block also exert downward force of magnitude B on the liquid. Hence option (3) is right.