The correct answer is Kutch.
Kutch is a district in the Indian state of Gujarat. It is the largest district in India by area, covering 45,652 square kilometers (17,612 sq mi). The district is located on the northwestern coast of India, bordering the Arabian Sea to the west and the Pakistani province of Sindh to the north.
Kutch is a major hub for salt production. The district has a long coastline and a number of salt pans, which are used to extract salt from seawater. Salt production is a major source of employment in Kutch.
The other options are incorrect. Bhavnagar is a district in the Indian state of Gujarat. It is located on the Gulf of Kutch, on the western coast of India. The district is known for its production of textiles, salt, and marine products.
Valsad is a district in the Indian state of Gujarat. It is located on the western coast of India, on the Arabian Sea. The district is known for its production of cotton, groundnuts, and sugar cane.
Jamnagar is a district in the Indian state of Gujarat. It is located on the western coast of India, on the Arabian Sea. The district is known for its production of oil, gas, and salt.