How Did the Developers of the Social Readjustment Rating Scale

How did the developers of the Social Readjustment Rating Scale measure the amount of stress caused by each of the items on the scale?

A) Each item was evaluated by a group of experts on stress and behavioral medicine.
B) They used the judgments of a large group of normal people who assigned the items life change units.
C) Scores were given to each item based on how much family members thought each event contributed to the death loved ones.
D) The items were weighted according to estimates from epidemiological research of how much each contributes to mortality.