Final answer:
Flat irons consist of two flat plates that are made of ceramic or metal, specifically options like titanium or tourmaline are common due to their heat conductivity and durability.
Step-by-step explanation:
Flat irons, which are used for styling hair, consist of two flat plates that can be made of several materials. The correct answer to what flat irons consist of in addition to ceramic is option C: metal. Metals such as titanium or tourmaline are commonly used in the plates of flat irons due to their excellent heat conductivity and durability. Unlike materials like wood, nylon, or plastic, metals can withstand high temperatures without melting or causing damage to the device or hair. High-quality flat irons often feature ceramic-coated plates that help to distribute heat evenly, preventing hot spots that can damage hair.