The correct answer is: a) Silver, turquoise, and coral.
Traditional Sikkimese jewelry often incorporates materials like silver, turquoise, and coral. Silver is a precious metal that has been used for jewelry making for centuries. It is a soft metal that can be easily worked into intricate designs. Turquoise is a semi-precious stone that is often used in jewelry because of its beautiful blue color. Coral is a type of marine animal that is often used in jewelry because of its bright red color.
The other options are incorrect because they are not materials that are typically used in traditional Sikkimese jewelry. Gold, diamonds, and rubies are all precious stones that are often used in jewelry, but they are not typically used in traditional Sikkimese jewelry. Brass, copper, and wood are all materials that are used in jewelry making, but they are not typically used in traditional Sikkimese jewelry. Plastic, glass, and beads are all materials that are used in jewelry making, but they are not typically used in traditional Sikkimese jewelry.