The correct answer is c) Idukki.
Graphite is a mineral that is composed of carbon atoms arranged in a hexagonal lattice. It is a soft, black, and lustrous mineral that is used in a variety of applications, including pencils, lubricants, and electrodes.
The largest deposits of graphite in India are found in the Idukki district of Kerala. The graphite deposits in Idukki are estimated to be around 100 million tonnes. The graphite is mined from open-pit mines and is then processed into various grades of graphite.
The graphite deposits in Idukki are of high quality and are used in a variety of applications, including pencils, lubricants, and electrodes. The graphite industry in Idukki is a major contributor to the economy of the district.
The other options are incorrect because they do not have significant deposits of graphite.
a) Wayanad is a district in Kerala that is known for its coffee plantations and wildlife sanctuaries. It does not have significant deposits of graphite.
b) Kottayam is a district in Kerala that is known for its rubber plantations and backwaters. It does not have significant deposits of graphite.
d) Ernakulam is a district in Kerala that is known for its commercial and industrial activity. It does not have significant deposits of graphite.