The correct answer is a) Thiruvananthapuram.
Lignite is a type of coal that is formed from plant material that has been buried and subjected to heat and pressure over millions of years. It is a soft, brown coal that is lower in energy content than other types of coal, such as bituminous coal and anthracite coal.
Lignite deposits have been discovered in certain areas of Thiruvananthapuram, Kerala, India. The deposits are located in the Neyyar and Karamana river valleys. The lignite is used to generate electricity and to produce fertilizer.
The other options are incorrect because lignite deposits have not been discovered in those areas.
b) Alappuzha is a district in Kerala, India. It is located on the Arabian Sea coast. The district is known for its backwaters, which are a popular tourist destination.
c) Kannur is a district in Kerala, India. It is located on the Arabian Sea coast. The district is known for its beaches, temples, and wildlife sanctuaries.
d) Kozhikode is a city in Kerala, India. It is located on the Arabian Sea coast. The city is known for its beaches, temples, and mosques.