How did Diocletian’s military reforms affect the Roman Empire?

They ended civil unrest in the empire.
They united the empire under a new capital.
They reduced the empire’s ability to expand.
They made the empire more vulnerable to invasion.

They united the empire under a new capital.

Explanation:

Diocletian's reforms had tremendous effects in the fate of the Roman Empire. He stabilized the crumbling empire and brought it back to its former glory.Diocletian's military reform included the 'tetrarchy', or "rule of four" system where the empire was divided into four sub-divisions all ruled by  great co-emperors.Under this reforms, Diocletian united the entire empire under a new capital called Nicomedia.