Just find the domain please I have found everything else

The graph shows the megawatts of electricity used on one day in one city. Complete parts a through f. a. Is this the graph of a function? No Yes b. What is the domain? (Type your answer in interval notation) c. Estimate the number of megawatts used at 9 A.M. 1600 MW (Round to the nearest MW as needed.) d. At which hour, 0-24, was the most electricity used? 15 hr (Round to the nearest hour as needed.) 13 C Megawatts (MW) 2500- 2400- Q 2300- 2200- 2100- G 2000- 1900- 1800- 1700- 1600- 1500- 1400- 1300- 1200- 1100- 1000- 900- 800- 700+ 0 4 8 12 16 20 24 Noon Hours (hr) Time Remaining: 00:51:57 Next