Which statement regarding channel spacing and bandwidth is true?

The first statement is true because it reflects the relationship between the bandwidth and channel spacing of different communication modes in terms of their operational needs and efficiency. TELEX, which is a teleprinter service that operates within the radiocommunications domain, typically requires a narrower bandwidth compared to voice communications. This is because TELEX transmissions primarily deal with text, which does not require the same level of audio fidelity that voice communications necessitate.

In the context of channel spacing, TELEX channels can be more closely spaced than voice channels without causing interference, given that text data does not occupy as much spectrum as voice signals do. Voice communications, on the other hand, require wider bandwidths to accommodate the full range of frequencies needed to reproduce human speech clearly and to prevent cross-talk between channels.

Thus, when comparing the two, the bandwidth and channel spacing for TELEX are generally narrower than those used for voice, which makes the statement accurate in characterizing the differences between the two communication modalities.