The correct answer is c) Kollam.
Kollam is the leading district in mineral sand mining in Kerala. The district is home to several mineral sand mines, including the Kollam Mineral Sands Limited (KMLS) mine. The KMLS mine is the largest mineral sand mine in Kerala and produces a variety of minerals, including ilmenite, rutile, and zircon.
The other options are incorrect. Ernakulam is a district in Kerala that is known for its manufacturing and tourism industries. Alappuzha is a district in Kerala that is known for its backwaters and rice cultivation. Kollam is a district in Kerala that is known for its mineral sand mining and fishing industries. Kasaragod is a district in Kerala that is known for its agriculture and forestry industries.
Mineral sand is a type of sand that contains a variety of minerals, including ilmenite, rutile, and zircon. Mineral sand is used in a variety of industries, including the construction, glass, and ceramics industries.