Which of the conditions listed could cause excessively low refrigerant pressure at the compressor suction of a TXV controlled refrigeration system?

Correct Answer: Option A — The system is low on refrigerant.

A shortage of refrigerant reduces mass flow through the system, starving the evaporator. The thermostatic expansion valve cannot maintain normal boiling pressure, resulting in an starved evaporator, low suction pressure, and insufficient cooling capacity across the refrigerated spaces.