Explanation:

Graphs are an integral part of statistical analysis and are used to represent data visually. There are several types of graphs used for this purpose, including line diagrams, bar diagrams, pie diagrams, and pictograms.

Line Diagrams:
A line diagram is a graph that displays data as a series of points connected by lines. It is used to represent trends over time or to show the relationship between two variables.

Bar Diagrams:
A bar diagram is a graph that uses bars to represent data. It is used to compare values across different categories or to show the distribution of data within a single category.

Pie Diagrams:
A pie diagram is a graph that uses a circle to represent data. It is used to show the proportion of data within different categories.

Pictograms:
A pictogram is a graph that uses pictures to represent data. It is used to make data more engaging and easier to understand.

The correct answer to the given question is option 'A', which states that a graph is a line diagram. This is because line diagrams are the most commonly used type of graph to represent data in a statistical analysis.