About three-fourths of world's cobalt, a metal required for the manufacture of batteries for electric motor vehicles, is produced by

Cobalt is a crucial metal for the production of batteries used in electric vehicles and other energy storage systems.

The Democratic Republic of the Congo (DRC) holds approximately half of the world's known cobalt resources and currently accounts for around 70% of global production.

Therefore, the Democratic Republic of the Congo (DRC) produces about three-fourths of the world's cobalt.

Hence, option (c) is the correct answer.