Some people believe that the World Trade Center collapse of September 11, 2001 was caused, not by foreign terrorists, but by high ranking American officials. The plotters, the story goes, wanted to make sure that the buildings fell (because plane strikes alone wouldn't accomplish their objectives?) and brought the towers down via pre-arranged, controlled demolitions. This explanation has several flaws.

Which of the following components of the explanation is unfalsifiable?

a. The conspiracy theory is incredibly complex. It would involve thousands of people at all levels of government being knowingly involved in a great evil, and it would further require that no one involved would admit to involvement even after seeing the devastating harm caused by their actions. The official explanation can much more simply account for the data.

b. The thermite that was supposedly used to bring down the towers leaves no trace. It would be impossible to discover that thermite had not been used since there is no method of detecting it. This is a demerit of the conspiracy, rather than a merit.

c. There is no real motive for such an attack. The conspiratorial explanation is that the attacks were a pretext for war. Generally, war is undesirable for political leaders and furthermore there has long been precedent for the commitment of American forces without any prior attack on the U.S.

d. The conspiracy theory is heavily reliant on eyewitness testimony. Some people at the scene claim to have heard explosions when the towers came down. It seems to be a mistake to rely on the impressions of onlookers in such a hectic situation.