The correct answer is D) Combustion occurs with no increase in pressure. The Brayton cycle, which is the thermodynamic cycle used by gas turbine engines, is characterized by combustion occurring at constant pressure. During the compression and expansion processes, the pressure remains relatively constant, unlike in the Otto cycle (used by internal combustion engines) where the pressure increases significantly during the combustion stroke. The other answer choices are incorrect because they do not accurately describe the key feature of the Brayton cycle, which is the constant-pressure combustion process. Combustion in a gas turbine causes an increase in temperature and volume, but not a large increase in pressure, as required by the Brayton cycle.