Read the passage carefully and answer the following question.
One theory of accidents is what experts call the Swiss Cheese model. A slab of swiss cheese has several holes, randomly and unevenly distributed over its surface. If several slabs are stacked together, it would be impossible for something to slip through unless all the holes happen to line up.
If even one slab doesn’t align, the impending catastrophe will meet a layer of resistance, and the worst is averted. Aviation professionals will tell you that plane crashes never happen for a single reason. There may be an identifiable primary factor, but it’s usually a chain of events, an array of circumstances neatly piling up.
Which of the following statements can be BEST concluded from the passage?