B. It made the leader of the Yamato clan emperor of the entire country.
After Prince Shotoku rose to power in 593, new laws, reforms and the first constitution started to shape the empire. These changes were influenced by China's political system.
After the Prince's death, the interest to reform the empire remained alive. One of these reforms was the Taika reform, which made the emperor a figure of prominent power over the people and their properties. A new code, called Taiho, was issued in 702 to settle the reforms, and once it was officially established, the leader of the Yamato clan became the emperor of the entire country.