What role did merchants from Venice, Italy play in the decline of the Byzantine Empire?

They competed successfully with the Byzantines for trade with Asia.
They gained positions in the Byzantine court and misled the emperors.
They advised the pope in his diplomatic efforts against the Byzantines.
They became allies of the Muslim caliphates, financing the latter's armies.

Question

What role did merchants from Venice, Italy play in the decline of the Byzantine Empire?

 They competed successfully with the Byzantines for trade with Asia.
 They gained positions in the Byzantine court and misled the emperors.
 They advised the pope in his diplomatic efforts against the Byzantines.
 They became allies of the Muslim caliphates, financing the latter's armies.

anonymous · Answer

Well, I know that the merchant's trade rought avoided the Byzantine Empire, thus they declined in trade, and as a nation. 

Is that a sufficient answer? Or do you need more detail?

anonymous · Answer

Do you know the answer? Like, A,B,C, or D?