The graph below displays a fire department’s response time, which measures the time from when the alarm is sounded at the firehouse to the time the first fire engine leaves the station. A histogram titled Fire Department Response Times has response time (seconds) on the x-axis and relative frequency on the y-axis. 20 to 30, 0.07; 30 to 40, 0.08; 40 to 50, 0.2; 50 to 60, 0.32; 60 to 70, 0.18; 70 to 80, 0.13; 80 to 90, 0.04.

Which interval accounts for the lowest percentage of response times?

20–30 seconds
30–40 seconds
70–80 seconds
80–90 seconds

I think its (D), 80-90 seconds. Someone check me.