Which one of the following statements correctly distinguishes a blackbody from a real body?
a) A blackbody has emissivity less than 1, whereas a real body has emissivity equal to 1.},{
b) A blackbody absorbs only visible radiation, whereas a real body absorbs radiation of all wavelengths.
c) A blackbody has zero reflectivity and zero transmissivity, whereas a real body can have both.
d) A blackbody emits radiation independent of its temperature, whereas a real body radiates only when heated.