Final answer:
Most elements that conduct heat are malleable and have free electrons, a characteristic of metals, making C the correct answer.
Step-by-step explanation:
The two properties that apply to most elements that conduct heat are malleability and the presence of free electrons. Malleable materials can be deformed without breaking, and the presence of free electrons is what allows the heat to be conducted. Therefore, the correct answer is C. Malleable and has free electrons. Metals typically exhibit these properties; they are known for their ability to conduct heat and electricity due to the sea of free electrons that moves thermal energy and electric charge through the metal lattice.