The dot plots below show the scores for a group of students who took two rounds of a quiz:

Two dot plots are shown one below the other. The title for the dot plot on the top is Round 1 and the title for the bottom plot is Round 2. Below the line for each dot plot is written Score. There are markings from 5 to 9 on the line at intervals of one. There are 2 dots above the mark 5, 3 dots above the mark 6, 4 dots above the mark 7, and 1 dot above the mark 8. For the bottom dot plot there are 6 dots above the mark 6, 2 dots above the mark 8, and 2 dots above the mark 9.

Which of the following inferences can be made using the dot plot? (5 points)

a
The range of each round is the same.

b
There is no overlap between the data.

c
Round 1 scores were higher than round 2 scores.

d
Round 2 scores were lower than round 1 scores.