ANS:B - black & rough

A hot body will radiate heat most rapidly if its surface is black and rough. This is because black surfaces absorb and emit thermal radiation more efficiently than white surfaces. The term "black" in this context refers to materials that are good absorbers and emitters of thermal radiation across a broad spectrum of wavelengths. Additionally, rough surfaces tend to emit radiation more effectively than polished surfaces because rough surfaces have more surface area and can emit radiation from multiple angles, increasing the overall emission of thermal radiation. Therefore, the correct option is: black & rough