Which of the following is true about SITOR (NBDP) ARQ mode?

SITOR (Ship to Ship and Ship to Shore Telex Over Radio), particularly in its ARQ (Automatic Repeat reQuest) mode, is indeed an interactive mode. In this mode, the communication involves a back-and-forth sequence where messages can be acknowledged or requested for retransmission if they are not received correctly. This interactivity is essential for ensuring the integrity of the message being transmitted, especially in a maritime context where reliable communication is critical for safety and operational effectiveness.

In contrast, other options describe characteristics or functionalities that don't align with the primary purpose of the ARQ mode. For instance, while some transmission protocols might repeat characters for error-checking purposes, ARQ relies on sending messages and receiving confirmations rather than simply repeating characters multiple times. The focus of ARQ is on interaction between the sender and the receiver to enhance communication reliability, distinguishing it from more straightforward broadcasting modes.