Deviations between estimated regression line and vertical deviations are classified as

The correct answer is D. residual terms.

Residual terms are the differences between the observed values of the dependent variable and the values predicted by the regression line. They are also called the errors of the regression.

Fixed terms are the parameters of the regression model, such as the intercept and the slope coefficients.

Indexed terms are the values of the independent variables in the regression model.

Variable terms are the dependent variables in the regression model.

Residual terms are important because they measure the amount of error in the regression model. The smaller the residual terms, the better the regression model fits the data.