Answer:
number of square feet in the townhouse.
Explanation:
When the relationship of two quantitative variables is assessed through plot then the scatter plot is made. Scatter plot shows relationship between two qualitative variables by showing dependent variable on y axis and independent variable on x axis.
When the relation between sale price of house and number of square feet in house is assessed then the sale price is dependent variable and square feet in house. Sale price is dependent variable because the price of house depends on the number of square feet of house. Thus, number of square feet in the town house will be plotted on the horizontal X-axis.