temperature difference of evaporator coil

[Gary]

Confusing dT with TD is common.

Delta-T (dt) refers to a change in temperature of a single medium. In this case, a drop in air temperature as the air flows through the coil.

RA - SA = dT

Temperature difference (TD) refers to the temperature difference between two mediums. In this case, the difference between the return air temperature and the low side refrigerant saturation temperature (saturated suction temperature aka SST).

RA - SST = TD

A coil does two things: It cools and it de-humidifies. The cooling shows up in the form of increased dT (lower SA temperature), but the de-humidification does not. When a higher proportion of the refrigerating effect is used to de-humidify, the dT is lower (more de-humidification means less cooling).

If the question applies to dT rather than TD, then the answer is D.