The correct answer is c) Thiruvananthapuram.
Amethyst and aquamarine are occasionally found in the state of Kerala, India. The most famous gemstone mine in Kerala is the Pazhayar mine, which is located in the Thiruvananthapuram district. The Pazhayar mine is a major source of amethyst, aquamarine, and other gemstones.
The other options are incorrect because they are not located in the state of Kerala. Thrissur is a city in the state of Kerala, but there are no known gemstone mines in Thrissur. Palakkad is a district in the state of Kerala, but there are no known gemstone mines in Palakkad. Ernakulam is a district in the state of Kerala, but there are no known gemstone mines in Ernakulam.
Gemstones are minerals that are prized for their beauty and rarity. They are often used in jewelry and other decorative items. Amethyst is a purple variety of quartz, while aquamarine is a blue-green variety of beryl. Both amethyst and aquamarine are popular gemstones.