The correct answer is D) Both A & B. The provisions for avoiding the build-up of ice on the intake air surfaces of a gas turbine plant are typically found in the inlet duct frame at the inlet to the engine (option A) and in the exhaust and intake ducting (option B). This is because the intake air surfaces need to be protected from icing conditions to ensure proper air flow and prevent disruption of the gas turbine operation. The other options are incorrect because the stack intake ducting (option C) is not directly responsible for preventing ice build-up on the intake air surfaces, which is the focus of the question.