The correct answer is C) 16 to 1. The designed compressor pressure ratio of the gas turbine compressor rotor shown in the illustration GT-0004 is 16 to 1. This is the typical pressure ratio for a simple-cycle gas turbine engine used in marine applications, such as those found on many US Coast Guard vessels. The high pressure ratio is achieved through the multi-stage design of the compressor rotor, which efficiently compresses the incoming air before it enters the combustion section of the engine. The other answer choices are incorrect because 10 to 1 and 12 to 1 are lower pressure ratios not commonly used in marine gas turbines, while 20 to 1 is a higher pressure ratio more typical of advanced aircraft engines rather than marine applications.