$A$ spring balance and a physical balance are kept in a lift. In these balances,equal masses are placed. If the lift starts moving upwards with constant acceleration,then:

• A
  The reading of the spring balance will increase and the equilibrium position of the physical balance will be disturbed.
• B
  The reading of the spring balance will remain unchanged and the physical balance will remain in equilibrium.
• C
  The reading of the spring balance will decrease and the physical balance will remain in equilibrium.
• D
  The reading of the spring balance will increase and the physical balance will remain in equilibrium.