A metal has a high concentration into the earth crust and whose oxides cannot be reduced by carbon. The most suitable method for the extraction of such metal is :

The most suitable method for the extraction of such metal is the electrolysis process

Strong electropositive metals like K, Ca, Na, Al, and Mg have extremely stable oxides. They are challenging to convert into metallic states by carbon reduction. These metals are obtained by electrolyzing the fused chlorides, oxides, and hydroxides that contain them.

Therefore, the electrolysis technique is the best option for extracting a metal with a high concentration in the Earth's crust and whose oxides cannot be reduced by carbon.

Hence the correct option is B