Need !

in order for radiation to transfer heat,
a electromagnetic waves must be transmitted
b objects must be in direct physical contact
c particles must circulate and move in a liquid or gas
d thermal energy must move from cold to hot objects

The answer is A.

Radiation is a type of heat transfer that transfer heat by electromagnetic waves. Outside the visual color range, we cannot see it. But sure almost everything is emitting and absorbing radiation right now. This type of heat transfer works in almost every environment, including vacuum.

Hope this helps