The season of strikes seemed to have run itself to a standstill. Almost every trade and industry and calling in which a dislocation could possibly be engineered had indulged in that luxury. The last and least successful convulsion had been the strike of the World's Union of Zoological Garden attendants, who, pending the settlement of certain demands, refused to minister further to the wants of the animals committed to their charge or to allow any other keepers to take their place.
from The Unkindest Blow, a short story by Saki
Which does "in which a dislocation could possibly be engineered" modify "Almost every trade and industry and calling" or "calling"?