Which was changes the sentence so that uses the active voice?
Beore the experiment by scientists, a decision was reached.
Scientists reached a decision about when to begin the experiment
A decision was reached with scientists about beginning the experiment.
The beginning of the experimentis a decision that was reached by scientists.

the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).

b. a system of government that provided a model for the united states.