Modulating control valves:
a. Are never used to control steam coils, regardless of inlet air temperature
b. Are used for steam coils where the condensate must be lifted to an overhead condensate return line
c. Is used for steam coils when the entering air temperature is below 1.5°C
d. Can be used to control steam coils when the entering air temperature is above 1.5°C
e. Should be oversized
Answer: D