Question: What type of signals, in addition to Metropolitan Beacon System (MBS) signals, are currently used for Terrestrial Beacon System (TBS) positioning in NG-RAN?
Option 1: Positioning Reference Signals (PRS)
Option 2: Synchronization Signals (SS) and Physical Broadcast Channel (PBCH) signals
Option 3: Cell-Specific Reference Signals (CRS) and Channel State Information Reference Signals (CSI-RS)
Option 4: Random Access Channel (RACH) preamble signals
Explanation: The correct answer is Option 1 because, according to the provided context, Positioning Reference Signals (PRS), in addition to Metropolitan Beacon System (MBS) signals, are mentioned as the current types of TBS positioning signals, notably relevant for OTDOA positioning methods.