Which type of data would be best displayed in a histogram?

A:the number of dental chairs donated each for the last 12 (range 1-9)
B:the number of students seen in a
school clinic that wore braces
C:the number of college students from the dental school that volunteered their time last month
D:the number of fluride treatments given to students each month for the last 60 months (range 40-620)