A wax candle floats vertically in a liquid of density twice that of wax. The candle burns at the rate of 4 cm/hr. Then, with respect to the surface of the liquid the upper end of the candle will:
| A. |
fall at the rate of 4 cm/hr |
| B. |
fall at the rate of 2 cm/hr |
 |
| C. |
rise at the rate of 2 cm/hr |
| D. |
remain at the same height |