The correct answer is C) Class C. A fire in the radio transmitter would be classified as a Class C fire, which is an electrical fire involving energized electrical equipment. According to the Coast Guard regulations, Class C fires involve fires in "energized electrical equipment where the electrical nonconductivity of the extinguishing media is of importance." Since a radio transmitter is an electrical device, a fire involving it would fall under the Class C category of fires. The other answer choices are incorrect because: A) Class A fires involve ordinary combustible materials, B) Class B fires involve flammable liquids and gases, and D) Class D fires involve combustible metals, which do not apply to a fire in a radio transmitter.