Question

a group of friends gather around a fire to stay warm. radiation conduction convection

Explanation:

Radiation is the transfer of heat energy by electromagnetic waves. When friends gather around a fire to stay warm, heat reaches them through radiation as the fire emits infrared radiation which warms their bodies without the need for a medium to carry the heat in the form of direct contact (unlike conduction) or movement of a fluid (unlike convection).

Answer:

radiation