Final answer:
A line graph is the most effective chart to illustrate relationships between concepts or steps in a process.
Step-by-step explanation:
A line graph is a type of chart used to represent data points in a series over a continuous interval or time span. It is particularly useful for showing trends and changes in data over time.
A line graph is often the most effective format for illustrating a relationship between two variables that are both changing. For example, time series graphs can show patterns as time changes, like the unemployment rate over time.