Which of the following sentences is a complex sentence? O Alex looked for Martha and Samuel at the train station, but they had already gone.
O Martha and Samuel arrived at the train station before noon, and then they waited for Alex.
O Martha and Samuel left on an early train, so Alex did not see them at the station.
O After they left on the train, Martha and Samuel realized that Alex must have gone to the bus station.

can you give me a hint

the thousand and one nights – or, as i prefer to call them in the following for purely practical reasons: the arabian nights – as we perceive them three hundred years after antoine galland’s epochal french adaptation bear a distinct arabic imprint. meanwhile, the commonly accepted model for their textual history acknowledges various stages in the conceptualization and effective formation of both the collection’s characteristic frame story and the embedded repertoire. the vast majority of tales in the preserved manuscripts of the nights has been integrated into the collection during two periods of arabic influence, the so-called baghdad and cairo periods (gerhardt 1963: 115–374). these “arabic” stages are preceded by an iranian version, probably dating to pre-islamic times, which in its turn profits from both structural devices and narrative contents originating from indian tradition. considering the eminent position that iran and iranian culture hold in the early stages of the textual history of the arabian nights, surprisingly few details are known concerning the collection’s relation to and its actual position within the iranian cultural context. in the following, i will discuss links between the arabian nights and iranian culture on several levels. in surveying these links, i will treat five major areas: (1) the iranian prototype of the nights; (2) tales of alleged persian origin; (3) persian characters within the tales; (4)persian translations of the arabian nights; and (5) the position of the arabian nights in modern iran