What type of heat transfer is heat that comes from a heat lamp in a bathroom?
conduction
convection
radiation
potential
my answer is radiation,
c. is it correct?

Yes your answer is correct. Radiation is the heat transfer that occurs when heat from the lamp is felt inside the bathroom. Unlike convection and conduction, radiation does not need any material to transfer heat. It does not rely on the contact made between the heat source and the heated object. In this case, heat is directly transferred to the environment through thermal radiation or infrared radiation. 

Best example of this type of heat transfer is the heat that comes from the sun that releases radiation into the atmosphere of the Earth.