Zone refining process is used for the:
A. concentration of an ore
B. reduction of a metal oxide
C. purification of metal
D.purification of an ore

Hint: Zone refining process is a special process. This method was invented by William Pfann. The other methods similar to zone refining for the particular use are distillation, liquidation, electrolytic refining and chromatographic methods.

Complete step by step answer:
-Zone refining process is used for the purification of metal.
-Metals are purified through this process to a very high degree. The other name of zone refining is called fractional crystallization.
-Ultra-pure samples of metals like germanium, silicon, boron, and gallium are obtained through this process.
-The principle behind this process is the impurities of the ingot or the ore of metals are more soluble than the pure metals of the solid state in the melt state. The detailed process is as follows:
An impure metal rod is kept in a container and the inert gas is filled in the container. Then, a circular heater is placed at the top surrounding the rod.The circular heater heats up the metal. After that, when the heater shifts to the next zone, the pure metal gets cooled and crystallized. The molten impurities go along with the movement of the heater to the next zone. In this way, the impurities get collected in the last zone and finally we can separate them from the pure metals.

So, the correct option is C.

Note: This process is also known as zone melting or floating zone process or travelling melting zone. The heater used is circular in shape and it is easy to move that is a mobile heater. The segregation coefficient (the ratio of the impurities in the solid state to the impurities in the liquid or melt state) is generally less than 1.