Research scientists need a certain type of bacteria to conduct an experiment. There are 100 bacteria in a certain culture. The culture grows at a rate of 70% daily. The scientists need at least 1,400 bacteria to conduct an experiment. What is the least number of days they must wait for the bacteria culture to reach a quantity of 1,400? (Hint: use a guess-and-check method to determine the lowest number of days that satisfy the requirement.) A. 4 days B. 5 days C. 6 days D. 7 days