The definition for a line plot.

The correct answer is: A display of data using a number line 

A line plot can be defined as a graph that displays data with the help of symbols above a number line showing the frequency of each value. It is used to organize the data in a simple way and is very easy to interpret.
* It is a graphical representation of the data on number lines using dots, crosses, or any other symbol.
* Each mark represents a specific quantity which is the scale of the graph.
* If n variables are present into a single field, then n symbols are drawn above the line according to it's frequency.

Line plot is defined as a graphical representation of a data on the number line using symbols.
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Representation of Line plot :

Here, Height of the students is the function and height's are taken on the number line and frequency regarding height such that there are 2 people with height 100 and 3 people with height 105 and so on.
* Hence, We can say that line plot is defined as data representation on the number line.