Why Does the Police Department Ask New Trainees to Practice

Why does the police department ask new trainees to practice their skills under difficult and unpleasant conditions?

A) to discourage cowardly people from joining the police department
B) to find out which trainees are likely to panic and weed them out
C) so they will not get impatient while waiting for their field assignments
D) so they will be less likely to panic in real-life conflicts