To prevent freezing of the steam coil when steam pressure at the coil inlet is too low, or is lost:
a. A second preheat coil is installed at the outside air inlet
b. A modulating steam control valve is installed at the coil inlet
c. A two-position steam control valve is installed at the coil inlet
d. Provisions are made to stop the fan and close the outdoor air dampers
e. Inverted bucket steam traps must be used
Answer: D