Answer please somebody I don't understand?

A ballet school wants to buy new slippers for students in a class. They collected the sizes and displayed them in a line plot.

A horizontal number line starting at 3.5 with tick marks every 0.5 units up to 8. The following values are labeled: the value of 4 has two dots, the value of 4.5 has one dot, the value of 5 has one dot, the value of 6 has 2 dots, the value of 6.5 has one dot, the value of 7 has one dot, and the value of 7.5 has one dot. The image is titled Ballet Shoe Sizes.

What is the range, and what does it mean in terms of this data set?

The range is 3.5, and it means that the data varies by a value of 3.5.
The range is 3.5, and it means that it is the value that occurs the most.
The range is 4.0, and it means that the data varies by a value of 4.0.
The range is 4.0, and it means that it is the value that is the smallest.