How did the avars contribute to the weakening of the byzantine empire?

the avars teamed with the powerful to overthrow zoe and theodora.
the avars formed a powerful kingdom along the danube river and attacked from this position.
the avars turned against the byzantines after initially them fight the slavs.
the avars used advanced greek technology to besiege the city of constantinople.

The correct answer is C) The Avars turned against the Byzantines after initially helping them fight the Slavs.

The Avars contributed to the weakening of the Byzantine Empire in that the Avars turned against the Byzantines after initially helping them fight the Slavs.

The Avas were a native group, northeast Caucasian group of people, that lived in what today is the Russian territory, close the Caspian Sea. Initially, they helped the Byzantine Empire in fighting the Slavs, but later they turned against the Empire. The Avars wars against the Byzantine Empire started in 568 and ended in 626.