A Nursing Professor Wishes to Determine If There Is an Association

A nursing professor wishes to determine if there is an association between her students grades and three independent variables (use of online tutorials, the use of quiz review sessions and participation in study sessions) . Her regression model has a significant R square (0.83) . She knows this means:

A) She should include all the independent variables in her model because they are significant.
B) She is unable to determine what the R square means without a p value.
C) There is a clinically significant relationship between the use of resources and final grades.
D) 83% of the variance in grades is explained by the independent variables included in the model.