Hydrologic scientists are trying to increase the safety of the drinking water for a local community. The scientists add a filtering system to all wells in the community and chart the contaminants in the water over time. The following graph shows the contaminants, in parts per billion (ppb), that were found in the water for a number of days after the filtering systems were added. 3000 2000 1000 10 15 20 Time in days 2017 FlipSwitch. Created using GeoGebra. Part A: How many days did it take the filtering system to significantly decrease the contaminants? Part B: Which option correctly describes the domain of the function? Select one answer that is completely correct for Part A and one answer that is completely correct for Part B. Contaminants in ppb B: The domain of the function is (4, o0), which describes the contaminant parts per billion. A: The filtering system took approximately 4 days to take effect, indicated by the vertical asymptote. B: The domain of the function is (-o, o0), which describes the time elapsed in days since the beginning of the study. A: The filtering system took approximately 1200 days to take effect, indicated by the vertical asymptote. B: The domain of the function is (4, co), which describes the time elapsed in days since the beginning of the study. A: The filtering system took approximately 4 days to take effect, indicated by the x-intercept. B: The domain of the function is (-0o, o0), which describes the contaminant parts per billion. A: The filtering system never made a significant effect, because the contaminant parts per billion increases over time.