Which investigation shows the transfer of heat energy in the absence of matter?

Question

Using a current through fluid to investigate radiation
Using particles in space colliding to investigate conduction
Using electromagnetic waves to investigate radiation
Using particle movement through a solid to investigate conduction

Answer 1

The investigation that shows the transfer of heat energy in the absence of matter is:

Using electromagnetic waves to investigate radiation.

Radiation is the transfer of heat energy through electromagnetic waves and does not require a medium (like matter) to occur. In contrast, conduction requires a medium with particles to transfer heat, and convection involves the movement of fluid, which also requires matter.