Of all the Arabic epic poems that have been popular at various times, only Sirat Bani Hilal is still publicly performed. Furthermore, while most other epics were only recited, Sirat Bani Hilal has usually been sung. The musical character of the performance, therefore, is the main reason for its longevity.

The argument is most vulnerable to criticism on the grounds that it

A. relies on evidence that is in principle impossible to corroborate
B. relies on a source of evidence that may be biased
C. takes for granted that a particular correlation is causal
D. takes what may be mere popular opinion to be an established fact
E. takes a sufficient condition to be a necessary condition

The OA is C