What Goal-Setting Technique Explained Why a Larger Proportion of One

What goal-setting technique explained why a larger proportion of one group of university staff members attended a health and safety training session, compared to the lower attendance seen in a second group of staff members?

A) They were given a more difficult goal.
B) They were given a more specific goal.
C) They were more committed to the goal.
D) They received more feedback about their progress.