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# Entrance Rate for Ceremony

SATMAT-VHD1GL

The doors to a high school auditorium were opened one hour before the start of the graduation ceremony. As the doors were opened, people started entering the auditorium. The graph above shows the number of people in the auditorium from the time when the doors opened until the start of the ceremony. According to the graph, at what time interval was the entrance rate approximately $15$ people per minute? (Calculator)

A

From $t=0$ to $t=10$

B

From $t=10$ to $t=20$

C

From $t=30$ to $t=50$

D

From $t=50$ to $t=60$