Explanation: MF-HF distress, urgency, and safety communications are conducted on specific simplex frequencies to maximize their reception by all potentially involved parties. For **non-GMDSS ships (A)**, which may maintain an aural watch on these frequencies, simplex operation ensures that all transmissions – both from the vessel in distress and any responding stations – are heard directly by everyone tuned in. This broad reception increases the likelihood of nearby vessels becoming aware of the situation and offering assistance. For **GMDSS or DSC-equipped ships (C)**, while a Digital Selective Calling (DSC) alert first establishes the initial call, the subsequent voice communication is moved to a designated simplex distress frequency. This allows not only the intended recipient but also any other vessel or shore station monitoring that frequency to hear the entire exchange, facilitating a shared understanding of the situation and enabling a coordinated response. Option **D** is incorrect because the primary objective is to allow *all* relevant parties – including other vessels and rescue coordination centers – to hear the distress traffic, not to restrict it. Simplex mode facilitates this widespread awareness.