The graph shown gives the estimated population (in thousands) of a bacterial culture as a function of the number of hours since observation began. What is the best interpretation of the -intercept of the graph in this context? 
The initial population was 50,000 bacteria.
The population decreases by 50,000 over 6 hours.
The population dropped by 50,000 in the first hour.
After 6 hours, the population is 50,000.
