The Term Tetrarchy Refers to Which of the Following

The term Tetrarchy refers to which of the following?

A) the division of the Roman empire into four regions under the rule of Diocletian
B) the policy that Roman rulers had to choose four men to succeed them, with the final selection to be made by the Roman Senate
C) the division of the Roman empire into two regions with four corulers instituted by Diocletian
D) the proclamation by Diocletian that the Roman empire was to have four main regional capitals