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Since the first dolphin was trained by the United States Navy in 1965 to help divers in their underwater home, Sealab II, many other dolphins have been drafted into the Navy. Originally dolphins were used as messengers or to answer calls for help. Today dolphins do much dangerous and necessary work as locating explosives hidden in the sea and helping ships navigate safely in war zones.
The main topic of the passage is ... .
The risky life of dolphins in the sea.
Dolphins used as carriers and helpers.
The search for mines in war zones.
Useful employment of trained dolphins for diverse navigational purposes.
The training of dolphins for entertainment and pleasure.
