A deep sea hydrophone began recording for 180 seconds as soon as it sensed a sound greater
than the threshold intensity of 200 underwater decibels (dB). The sound intensity, I, in dB
reached a maximum at 60 seconds after recording and then gradually decreased for the next
120 seconds. If t is the number of seconds since the beginning of recording, which of the
following graphs in the tI-plane could model the sound?