Step 1: Understanding correlation plots.
A correlation plot visually depicts the relationship between two variables. To determine the effect of variable \(X\) on variable \(Y\), a plot is necessary with both variables represented on the axes.
Step 2: Evaluating options.
- Option 1: Bar graph – Suitable for comparing categorical data, not for showing variable correlation.
- Option 2: Pie chart – Designed to display proportions or percentages, not relationships between variables.
- Option 3: Box plot – Used to illustrate distribution, spread, and outliers, but not direct correlation.
- Option 4: Scatter plot – Positions one variable on the x-axis and the other on the y-axis, thereby directly illustrating correlation. This is the correct choice.
Step 3: Conclusion.
Scatter plots function as correlation plots by visually representing the relationship (positive, negative, or absent) between two continuous variables.
Final Answer: \[\boxed{\text{Scatter plot}}\]