Concerning frost appearing on one set of evaporator coils of a multi-box, direct expansion type refrigeration system, what is true?

Correct Answer: Option B — the frost can be removed by passing hot vapors through the coils

Frost accumulation on direct-expansion multi-box evaporator coils acts as an insulating thermal barrier, reducing heat transfer efficiency. Hot gas defrosting introduces high-pressure, warm compressor discharge vapor directly into the coils to rapidly melt accumulated frost from the inside out.