Track lighting is not permitted to be installed less than ____________ above the floor unless it has an open-circuit voltage of less that 30 volts RMS. Select one:
a. 5 feet (1.5 m)
b. 6 feet (1.8 m)
c. 6 feet 7 inches (2.0 m)
d. 7.5 feet (2.3 m)