2017 Pascal Problem 6

At six different times on Canada Day in 2016, the number of people at the Pascal Zoo were counted. The graph to the right shows these results. During which of the following periods did the number of people at the zoo have the largest increase?

\textbf{(A)}\ 9:00 a.m. to 10:00 a.m.\quad \textbf{(B)}\ 10:00 a.m. to 11:00 a.m.\quad \textbf{(C)}\ 11:00 a.m. to 12:00 p.m.\quad \textbf{(D)}\ 12:00 p.m. to 1:00 p.m.\quad \textbf{(E)}\ 1:00 p.m. to 2:00 p.m.

If there are no answer choices shown, enter a numerical answer.

Full credit to this problem is given to the CEMC, you may view all Pascal contests here.