Which of the following statements is true regarding line temperatures?

The correct understanding of line temperatures in residential air conditioning systems aligns with the notion that each type of line carries different substances at varying degrees of heat.

When evaluating liquid lines compared to suction lines, it is important to recognize that liquid lines, which carry refrigerant in its liquid state to the expansion device, are typically cooler than suction lines, which transport the refrigerant in its gaseous state back to the compressor after it has absorbed heat from the indoor space. This principle underscores the nature of their respective functions within the system and the physical states of the refrigerant they carry.

Additionally, the statement that liquid lines have less heat content than hot gas discharge lines is also true. Hot gas lines, which transport refrigerant in a gaseous state directly from the compressor, typically handle significantly higher temperatures due to the compression process that raises the refrigerant's heat content.

By acknowledging that liquid lines are cooler than suction lines and have less heat content compared to hot gas discharge lines, all the statements provided essentially hold true. Therefore, saying that all of the statements are correct is justified in the context of understanding line temperatures in residential AC systems.