Question

what is the only type of heat transfer that can pass through a vacuum? radiation convection

Explanation:

Heat transfer occurs via conduction (through solids), convection (through fluids - liquids and gases, involving bulk movement of fluid), and radiation (via electromagnetic waves). In a vacuum, there are no particles (as in solids, liquids, or gases) for conduction (which needs direct particle - to - particle contact) or convection (which needs fluid flow). Radiation, which is the transfer of energy in the form of electromagnetic waves (like infrared radiation), does not require a medium. So, it can pass through a vacuum.

Answer:

radiation