System voltage

In this diagram, if the first load is a 120V computer, what is the second load shown?
A. single phase transformer, 480/120-240V
B. 208V 3-phase motor
C. 208V heater, single phase
D. 277V discharge fluorescent lighting

AnswerC. 208V heater, single phase. Neutral to any single panel bus = 120V. A load connecting two panel buses (not neutral) is 208V single phase; between three panel buses is 208V 3-phase. Since the computer is 120V, system voltage cannot be 277/480.
ARE 4.0 exam prep: BS