For the multiple regression equation developed to predict fuel efficiency (in $\text{mpg}$) of cars based on their engine size (in $\text{L}$), vehicle weight (in $\text{kg}$), and horsepower, the linear correlation coefficient ($r$) was found to be $r=-0.803$.
(i) What is the value of the coefficient of determination ($R^2$)?
(ii) What practical information does the coefficient of determination give in this context?

(i) $R^2=0.803$

(ii) The correlation between engine size and fuel efficiency is $64.5\%$

(i) $R^2=0.645$

(ii) $64.5\%$ of the variation in fuel efficiency can be explained by engine size, vehicle weight, and horsepower

(i) $R^2=0.645$

(ii) Increasing engine size, vehicle weight, and horsepower causes a $64.5\%$ reduction in fuel efficiency

(i) $R^2=0.803$

(ii) The model predicts fuel efficiency with $64.5\%$ accuracy