A repeater is a device that receives a signal and then retransmits it, typically to extend the range of the transmission. It does not perform any analysis or processing of the data, such as checking Layer 2 or Layer 3 addresses. Its primary function is to regenerate and amplify the signal to combat the attenuation and distortion that occurs over long distances. This makes option B, which describes a device that receives and retransmits a signal without analyzing the data, the best description of a repeater.