Which Part of Agnew's Strain Theory Has Yet to Be

Which part of Agnew's strain theory has yet to be extensively empirically tested?

A) Whether presentation of noxious stimuli can cause strain or is stressful
B) Whether strain is more likely to lead to crime when the strain is seen as unjust
C) Whether the presence or absence of social support is an important condition
D) Whether exposure to strain increases the likelihood of engaging in crime