The Example in the Text Predicting Distress in Cancer Patients

The example in the text predicting distress in cancer patients used distress at an earlier time as one of the predictors. This was done

A) because the authors wanted to be able to report a large correlation.
B) because the authors wanted to see what effect earlier distress had.
C) because the authors wanted to look at the effects of self-blame after controlling for initial differences in distress.
D) because the authors didn't care about self-blame, but wanted to control for it.