1. The problem asks to identify the explanatory variable when predicting the distance a baseball travels based on the speed it was hit. 2. The explanatory variable is the variable that is used to explain or predict changes in another variable (the response variable). 3. Here, the researcher wants to predict distance based on speed, so speed is the explanatory variable. 4. Therefore, the correct answer is: Speed. 5. For part (b), the scatter diagram should have speed on the x-axis and distance on the y-axis to reflect the explanatory and response variables respectively. 6. Among the options, Graph C shows speed on the x-axis (90 to 120 mph) and distance on the y-axis (330 to 480 feet) with points closely aligned in a positive linear trend, which matches the expected relationship. Final answers: - (a) Explanatory variable: Speed - (b) Correct graph: Graph C