Comparing Strike Intensity in Canada Against Other Countries Is Difficult

Comparing strike intensity in Canada against other countries is difficult because of all but which one of the following?

A) inclusion in some countries of workers disrupted by yet not directly involved in a work stoppage
B) exclusion of work stoppages staged for political purposes by some countries
C) differences in threshold of person- days lost
D) exclusion of certain industries from statistics in some countries
E) Canada's work stoppage statistics don't include lockouts.