Explanation: A public coast station is authorized to operate according to the specific privileges outlined in its radio station license. If the license includes authority for using telegraphy, even if its primary mode is high frequency narrow-band direct-printing (NB-DP), then it may establish contact using telegraphy. This ensures compliance with regulatory provisions. Additionally, a fundamental requirement for all radio operations, regardless of mode, is to avoid causing harmful interference to other authorized users. Option A is incorrect because licenses can, and often do, permit multiple modes of operation. Option B is incorrect as ship tonnage is generally unrelated to a coast station's permissible communication modes. Option D is incorrect because the presence or absence of specific calling devices on a vessel does not grant the coast station the fundamental authority to use a different transmission mode; that authority must come from its own license.