The correct answer is option 4, mica. Mica is a mineral that is widely used in various industries, including the cosmetics, electrical, and construction industries. India is the largest producer and exporter of mica in the world, accounting for a significant share of the global mica trade. Mica exports from India contribute to the country`s economy and provide employment opportunities for many people involved in the mica mining and processing industry. It is important to note that while India is a major exporter of mica, it is not the leading exporter of coffee, cotton, or manganese, as stated in options 1, 2, and 3 respectively.