ANSWER:
1st option: Radiation
Explanation:
Radiation is the transfer of heat energy by electromagnetic (infrared) waves and is very different from conduction and convection. Conduction and convection take place when the material being heated is in direct contact with the heat source. In infrared heating, there is no direct contact with the heat source. Infrared energy travels in a straight line through space or a vacuum (similar to light) and does not generate heat until it is absorbed. The converted heat energy is then transferred into the material by convection or conduction.
Which means that in this case, the heat transfer occurs by radiation.