1. The problem asks which type of graph is best to show the average rainfall in a city every year for ten years. 2. To represent data over time, such as yearly rainfall, a graph that shows trends or changes across years is ideal. 3. A line graph connects data points in chronological order, making it easy to see increases or decreases over time. 4. A bar graph can also show yearly data but is better for comparing quantities rather than trends. 5. A double bar graph compares two sets of data side by side, which is unnecessary here. 6. A circle graph (pie chart) shows parts of a whole at one point in time, not changes over years. 7. Therefore, the best choice is a line graph to clearly show average rainfall changes over ten years. Final answer: line graph