Explanation: A bilateral radio direction finder (RDF) determines a line of position (LOP) from the receiving station. This bearing indicates that the transmitting, or "originating," station is located somewhere along that specific line of direction. Therefore, the line passes through the originating station. Option B accurately reflects this: the bearing provides a line along which the transmitting station must lie. Option C, "A line of direction can read in either direction," describes the characteristic 180-degree ambiguity of a bilateral RDF. While true, it explains *how* the bearing is interpreted (it doesn't distinguish between two opposite directions on the line) rather than *what* the bearing fundamentally indicates about the source's location. The primary indication is that the source is on *that line*. Option A is incorrect because the bearing is between two stations (the RDF and the originating station), but the phrasing "passes through two stations" is unclear and doesn't precisely describe the line of position to the source.