The correct answer is B) With a condenser fitted with a single fan driven by a multi-speed electric motor, the fan speed would decrease under low ambient temperature conditions. The reasoning behind this is that in a refrigeration system with an air-cooled condenser, the fan cycling control pressure switch is designed to maintain the proper high-side pressure by adjusting the fan speed. When the ambient temperature is low, the condenser is able to reject heat more efficiently, causing the high-side pressure to decrease. The fan cycling control pressure switch will then reduce the fan speed to prevent the high-side pressure from dropping too low, which could lead to other issues in the system. The other options are incorrect because they do not accurately describe the behavior of the fan cycling control pressure switch in response to changes in ambient temperature. Option A is incorrect because the fan speed would increase, not decrease, under high ambient temperature conditions. Options C and D are incorrect because they do not apply to a system with a single fan driven by a multi-speed motor.