The appropriate domain for the problem would be based on the time \( t \) since the scientist is observing the bacteria population over a duration of 4 hours.
In this scenario, since the scientist checks the population in 4 hours, the time \( t \) should start from 0 (the beginning of the observation) and go up to 4 hours (the duration of the observation). Therefore, the suitable option for the domain is:
Option #3: \( 0 \leq t \leq 4 \).