Astudent streaks a plate using inoculum from a broth culture tube. the culture tube was labeled escherichia coli, indicating that the culture was composed of a single bacterial species. which of the following best explains the unexpected plate result shown here after incubation?

For this problem, I think you missed to include the observation or the result of the incubation that has to be shown. However, I think that this problem is talking about not just a single species growing in the plate. This is due to unsterilized materials used and/or in the contamination from the procedure of the streaking itself. 

Oi oi oi oi oi oi  i think it is true

Yes yes yes very good