What conclusion can be determined from the dot plot below? A dot plot showing two dots above 2, three dots above 3 five dots above 4, three dots above 5, and two dots above 6.

(3 points)

a
The median of the data set is 3.

b
The mean of the data set is 3.

c
The range of the data set is 5.

d
The number of observations is 15.