What is the main purpose of representation through a graph?

The main purpose of representation through a graph is to illustrate relationships between economic variables. Graphs provide a visual representation that makes it easier to understand how one variable affects another or how multiple variables interact within an economy. For instance, a graph might depict the relationship between supply and demand, helping to show how price changes can influence the quantity of goods sold. This visual method enhances comprehension of complex data sets, enabling quicker insights into trends and correlations that might be harder to discern through text or numbers alone.

Other options, while relevant to graphical representation, focus on more specific uses of graphs. For example, visualizing economic predictions is indeed a purpose of graphs, but it is somewhat narrower, as it concentrates on future trends rather than illustrating broader relationships. Tracking historical data is also an important role for graphs, especially in understanding past economic conditions, yet it does not directly address the relational dynamics at play. Persuading investors can be a secondary benefit of well-presented data but is not the fundamental reason for using graphs in economic analysis. Thus, option B encompasses the core utility of graphs in economics.