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 assigned the items life change units based on the judgments of a large group of normal adults.
C) Scores were given to each item based on how much family members thought each event contributed to the death of a loved one.
D) The items were weighted according to estimates from epidemiological research on how much each contributes to mortality.