Question

one of the first things vladimir i did after he became the ruler of kiev was to
force the population to submit to his authoritarian rule.
make orthodox christianity the state religion.
isolate kiev so that trade virtually stopped.
create a strong military for kievs defense.

Explanation:

To solve this, we recall historical facts about Vladimir I of Kiev. Vladimir I is known for converting to Orthodox Christianity and making it the state religion of Kievan Rus'. The other options are incorrect: he didn't primarily focus on authoritarian rule (first option), isolating Kiev would contradict trade importance (third), and while military was important, his key early act was religious conversion (fourth is less accurate as the primary first act here).

Answer:

B. make Orthodox Christianity the state religion.