Which of the following statements concerning SITOR (NBDP) communications is true?

In ARQ, each character is transmitted twice, about 250 milliseconds apart.

In ARQ, the "information sending station" will transmit a block of three characters that the receiving station will subsequently acknowledge or request be retransmitted.

In ARQ, the "information sending station" transmits a block of three characters twice, about 250 milliseconds apart.

SITOR (NBDP) communications can be used to contact a NAVTEX transmitting station when requesting a repeat transmission of a missed NAVTEX message.

Which of the following statements concerning...