Answer:
a. A line graph presents continuous and linked data, while a scatter plot presents unlinked data.
Explanation:
In this case, the first option is the correct answer because a line graph represents a certain amount of data, which is distributed using two variables (x and y), and it has continuity, this means that each (x,y) representation is followed by another, and another, in a straight line. In other words, when the relation between variables is proportional, their representation is a graph.
On the other hand, a scatter plot is a diagram that display values for two variables, but they don't have such perfect order, therefore, they are not represented by a straight line. A scatter plot can show a average relation between variables, that help to determine the type of relation between.
So, basically, the difference between is about the order of the data, one perfectly ordered, the other without such perfect order.