A thermoelectric thermometer is made . of copper-iron thermocouple. One junction is placed in melting ice and the other end is placed in a bath, whose temperature is continuously increased from 0°C to 600°C. The current in the galvanometer :

• A

  remains constant

• B

  constantly goes on increasing

• C

  first increases and then decreases to zero 

• D

  first increases, becomes maximum and then decreases to zero and finally reverse its direction